Typescript is already supported when you set it up using the documented "npm create svelte@next".
It has cool routing, backend etc but even if you don't care about any of it, you get free hot reloads. And with the new version, you can create it as if it was your average svelte app, just avoiding + in file names and using +page.svelte as your main entry point.
For styles, if you care about styling a bit more than default styles (mvp.css or bulma/bootstrap/similar), I'd recommend using tailwind's better clone windicss, which has great svelte integration (including editor extensions for autocomplete and highlight), and writing styles is quicker than using normal css.
You can also use scss/sass/similar in style blocks, you only need to install node-sass and set "scss"/"sass" as the lang of the style block.