There is a plugin for prettier[1] and for eslint[2]. Both work reasonably well. I hear there is good support for VSCode, but I haven't tried.
[1] https://github.com/UnwrittenFun/prettier-plugin-svelte [2] https://github.com/sveltejs/eslint-plugin-svelte3
Prettier works with Svelte as well. Here are some hints how to use that with Vim https://blog.ffff.lt/posts/vim-and-svelte/
Is there an auto formatter that makes my code shift around and have one-true-style? This is a most for any long lived project as it avoid all bikeshedding discussions about style. We use Prettier for JS, and mix format for Elixir, at work.