What do you do in a men's changeroom?

Hello, I am almost a year on T. I have had no surgeries, and I pass most of the time (at least as androgynous). I've been thinking about hitting the local gym/pool here in my town, but I am terrified of going into the men's changeroom because I have no clue what to expect.

Do men usually change butt naked in the main area? Are there stalls you can change in and is it seen as weird if you do so? What are the social intricacies of men changing in the same room?

I have autism, and so this may seem like dumb questions but I genuinely have no clue what to expect. I figured this was the best place to ask.