Emacs manual is great, at least skim it to see what's out there in stock Emacs.
Look at what Spacemacs provides in packages: these are most likely the most popular extensions. You don't need to use Spacemacs, but this is the closest to the curated list of useful packages Emacs has (would be glad to be proven wrong - is there a better list?), so at least reading through it will give you an idea what could be added to Emacs to make it more useful.
LSP support is a gift to all non-mainstream-IDE users. Use it.
"Mastering Emacs" is a good book: https://www.masteringemacs.org/book, I wish it was available when I started.
Be aware that many Emacs packages are terribly outdated and not very good to start with. Don't try too hard to make work something that sounds good on paper: if it doesn't work, or cumbersome to configure or use then look for alternatives. Over time I got rid of most of the packages I tried.
Learn some Elisp. It's not a large language, and knowledge of it makes making Emacs lifestyle improvements trivial.
P.S: It helped that at 1998 IDEs were too slow to run on a computer I could afford, so I stick to Emacs and eventually got better at it.