We would definitely recommend getting a clip-on tuner alongside your first guitar purchase. It’s one of the most important accessories and you’ll get a lot of use out of it. No guitarist worth their salt will be caught without a tuner, and it also helps you understand your first bits of music theory too.
Other accessories like guitar straps and guitar cables are instrument dependent. Most acoustic guitars are usable without a guitar strap thanks to their large body size. Electric guitars on the other hand can be unwieldy to play sitting down without a strap, so it’s worth investing in one if you have an electric as your first guitar.
If you’re going the electric guitar route, then you’ll have to get yourself a beginner guitar amp to go with it, as well as a guitar cable to plug it in. These are worth bearing in mind when you’re budgeting for your first purchase, as your guitar won’t be at its best without them.