I worked about 3.5 years at 2 huge companies, one as an employee (company #1) and the other as a consultant (company #2) as a developer.

There will often be inertia, delays, and even silence when having to go through organizational processes. It took almost 2 weeks for me to receive my laptop at company 1, and then I sat waiting for a week for word of security clearance for a piece of software. At company 2 I started applying for internal full-time positions a month and half before my contract was not going to be renewed (more on that later). I got a single in person interview (after waiting a month for pointless phone screens) my final week. The first few weeks after I left I was getting pinged asking for phone screens on positions I had applied to earlier.

There will be key people who carry tremendous weight politically, fiscally, and operationally. Finding them and making yourself visible/useful will be tremendously beneficial. I was lucky that both people who interviewed me fit this bill. I ended up getting moved into better, more enjoyable roles as a result. The security clearance I mentioned previously was resolved within a few hours of my direct manager emailing the security team manager (who she knew) asking what the status was (I was denied and they never bothered to inform me). These people are valuable for getting you where you want to be in the company, and tend to be more visible internally which is likely to make you more visible as well if you working with/for them.

There are going to be organizational decisions that are inexplicable, and there are limitations to the power of the people I mentioned above. At company 2 the first team I was on was one of 5 that were working on a single web product. The product lead was invaluable due to his domain knowledge and product skill. When I talked to him my final week he told me he was being moved onto another team during a key phase of his current product. The final team I was on myself and another dev was ineligible for FTE because we weren't physically located in one of the 3 areas the team members were located, even though the entire team itself was remote and they had been unable to hire new developers for the past couple of months that we were there.

Sometimes the company is rigid to the point of it being painful, and you're told "That's just how we do it here". We were expected to release a fully fleshed out, bug free product by a set date with zero wiggle room. This happened despite not having anyone to onboard it to for almost a month after release, after which it was barely used because the company decided to focus their efforts elsewhere.

Make a point to have a solid grasp of what is going on in other teams and the company at large. This will help you in seeing any funding/resource changes coming that will directly impact you.

Be mindful of politics and pick your battles wisely. You may not want to do one or both, but knowing who pulls great weight and who is aligned with who should keep your role cleaner.

There are likely going to be people who don't pull their weight, and they can even be above you in rank. Often times this is well known and there are reasons why, even if it's something as silly as the company doesn't fire FTE.

Meetings. There will be more of them than are needed, longer than is needed, and where you aren't needed.

Sometimes teams/groups can have drastic culture changes from the company at large. It can be remote vs in-office, everyone on the team works daily together in a large office (ugh), communication styles (email vs chat vs phone), lunch together/alone, etc.