Four strategies I can think of right now, but this is off-the-cuff and not written very well...

First, even if you have an opinion, regardless of how strong it is recognize most of the time you don't have to voice it or lead with it. Electing to not do so makes it easier to continue not doing so. To make progress on this, try not leading with your own opinion in a conversation, first ask about others' and linger on them. Occasionally be fine with "I don't know" even if you think otherwise. Play devil's advocate/contrarian with your own opinions when you can, see if you can make an almost convincing case for an alternative. See if you can find roots of disagreement that are ultimately stylistic in nature -- de gustibus non est disputandum -- and enjoy the diversity. Maybe there are tradeoffs you can elaborate. (Consider an analogy from table tennis on a grip style: https://gregsttpages.com/guide-to-table-tennis/beginners-gui... Could you write something similar for one of your opinions? Maybe you have an opinion about programming language typing?)

Second, "make your beliefs pay rent". If your beliefs don't actually make you predict how the future will unfold any differently depending on whether your belief is right or wrong, it's a waste of space, better to drop it. It's also a good idea to inspect your opinions to see what could maybe change your mind about them. Suppose you strongly feel X is true. Now imagine X were in fact false -- how could you tell? If you can't think of any way to tell, why do you believe X is true now? For any new X, see if you can think up little experiments or data gathering exercises (even polling some friends is data, weak as it may be) that could give you more information one way or another. If you can't, it's better to just remain ignorant about whether X is true or false, and be a friend to "I don't know, what can we do to find out more?" Maybe later on you get a little supportive data one way or another, but keep things fundamentally probabilistic and you'll be less tempted to express positions very strongly. It may help to think in terms of bits instead of raw probabilities, you can transform a probability to bits with log_2(p/(1-p)), note that ignorance (50%) is 0 bits, a single bit of evidence jumps you to 66% (or 33% the other way), but you need 3.17 bits to reach 90% and 6.6 bits to reach 99%. To be 99.9% sure something is true, you really need to have 10 bits of distinguishing evidence you can point to. Evidence from some e about proposition x in bits is log_2( P(e|x) / P(e|!x) ). Stop letting yourself hold or express an idea strongly if it doesn't reach a high enough threshold. When you do have a high threshold, be happy that you can justifiably hold such a position very strongly; your main concern is probably going to be political consequences for whether it's wise or unwise to talk about it, or talk about it outside certain contexts. (Many people are happy to hear strong authoritative-sounding things from an authority at church, related to church topics, but some other strong opinion from the same authority, even if justified, about something else and in another context, can raise hackles.)

Third, "When you don't create things, you become defined by your tastes rather than ability. Your tastes only
narrow & exclude people. So create." --why the lucky stiff. Think about how many hours you poured into the last fruitless argument strongly advocating for something. What if you had put those hours into making something instead? (Or heck, even something like playing lots of video games is probably better for you than to always be arguing with people if all you're doing is feeling and causing negative feelings from it.) Related to 2, perhaps you can even make something that gives a direct demonstration why your opinion is likely to be correct, rather than just rehashing arguments. Don't expect to convince many people though, the main benefit is that making things is a better use of your time and may even surprise you if you discover in the process that something you thought was true wasn't the case, at least all the time.

Fourth, consciously gamify and try to have fun, especially about opinions that aren't paying their rent but you want to share anyway, or even taste differences like not liking mushrooms. Sort of similar to the 'strong opinions loosely held' mantra, it's just a commitment to treat many conversations where you share your opinions and even get a bit passionate as just bar-talk; as a means of having fun; playing a game. This is also a way to get out of sticky situations around 1 where you're basically being forced to generate an opinion about something you haven't really thought much about. Because conversation can be boring and tiresome if you are constantly qualifying yourself with the appropriate hedges and humble admissions and specific probability estimates and language, it can be more fun to just say a simplified and maybe even outrageous version of what you're thinking and go from there, especially if you're doing it off the cuff on request, but beware you may hurt some feelings if the other person doesn't really want a conversation about the thing but instead is just looking for support. For yourself, try not to get too upset when you seem to be losing on some argument, or that you're not changing any minds, and even if you call each other names don't let it get in the way of an actual friendship outside of the discussion. Lots of people in gaming say very unkind things about their opponents or their mothers, and in the actual game there's usually ebbs and flows of winning and losing or doing well and poorly, but for most people it's just not very serious and a way for them to have fun. If you can get your discussion partner into the same frame of mind, you can have wildly different opinions yet not let that get in the way of having a good time together. The proverbial political Thanksgiving conversation is an instance of this -- your family may have terrible political takes, and they may think the same about you, and you can even get heated and emotional during dinner, but the next day, the healthy attitude is that hey, you're still family, the argument was more of a game than something serious, you don't need to blacklist each other.