Depends on what exactly you want to change. Lsp can do a lot but only in very simple changes.

Intellij when I used to use it had a lot great features like refactoring, extracting part of code as a function, renaming and creating empty classes/boilerplate but that's it

In current job I can order LLM to take data sink from other endpoint and write new with given URL. It will fetch from endpoint, check what it gives, compare with other and write new sink. Then it needs polishing because it always create something as awful as possible with cloning data all around but the most boring and soul sucking part is done