Came here to recommend ast-grep too!
If your editor of choice supports an extension (vscode does for example) it's a very easy on-ramp for a better search/replace than regex offers. It's syntax-aware so you don't need care about whitespace, indentation etc. Very easy to dip your toes in where a regex would get complex fast, or require multiple passes.
I converted a codebase from commonjs to esm trivially with a few commands right after first installing it. Super useful.
I hope LLMs eventually start operating at this level rather than raw text. And likewise for them to leverage the language server to take advantage of built in refactorings etc
I don't know which editors support this but there's also, for lack of a better word, context aware grep. For example, search and replace foo with bar but only inside strings, or only inside comments, or only variables, or only methods, not class names (maybe ast-grep does this).