SEO audit - literally what happens?

Hey guys, I'm building my career in SEO and I wanna know from some experienced people about what they do in a SEO audit. I'm literally asking what do you guys do? How do you proceed? I've seen many videos and did some courses, but it feels incomplete. I don't have anyone to guide or mentor in this, so any help would be great. Overall, what aspects or areas do you put in your final excel sheet?