I am totally fascinated by programmers who don't use many of the IDE features I take for granted today: autocomplete, language servers, and recently copilot

So to the devs who don't use these tools, how do you do it? Do you just remember every type and field in a codebase? What does your flow look like?

One example is that I cannot live without the language server go-to-definition feature. What do you do if you need to look up the definition/implementation of some function which is in some other file?