I know others are suggesting workout here so it thought I'd contribute back. I had a lot of success following Julian Shapiro's guide I'm how to build muscle [1], like so much so that I had to get rid of a few shirts because my arms wouldn't fit anymore.

It's detailed in explaining multiple faucets including nutrition and rest, I didn't follow every source he listed but he claims to have done quite a bit of research regardless everything is listed.

[1] https://www.julian.com/guide/muscle/intro