Yes, I try to learn the language well enough that I know the parameters of common functions. If I don't, I consult the docs. If I need to find the definition of a function in another file, I use grep.
Disclaimer: I do use LSPs extensively, but they do what they are intended to do when I explicitly ask. Offer completions. Format code. Organize imports. All that is available, but only happens when I ask. Same happens where there's no LSP support, and basically the same commands depend on ripgrep, fzf, semantic-grep, external linters and formatters, and plainly compilers.
Me and my tools take turns. It's almost 2025, practically everybody agrees that concurrent mutation of state is a source if trouble.
I'm the same way. I have never, ever been pleasantly surprised by auto completion when I did not explicitly enable it -- can't think of on instance of me doing this, either. In particular, web-based code playgrounds, IDEs, etc. auto-inserting quotes and parentheses drive me mad. Google Docs also frustrates me with their word/phrase suggestion widget that I can't seem to ever fully turn off.