Depends on whether or not the following is set:

    export const prerender = true;

If it is, it IS in fact compiled to HTML. :-) https://kit.svelte.dev/docs/page-options#prerender

Compilers are awesome.

This assumes you are using SvelteKit, not vanilla Svelte

    npm create svelte my-app

Creates a SvelteKit app now, not plain Svelte. That said, you can easily disable the server-side portion.

    export const ssr = false;

The important difference to note compared to React, is that Svelte doesn't virtualize the DOM. It works in the same way vanilla JS works when it comes to DOM manipulation.

Even though it is compiled, you are still working closer to the browser. You can still use all vanilla JS DOM manipulation methods in your code and it will work as expected. Which is an enormous advantage over React, at least for me.