Customizing website html with gulp pug sass?

Question

HTML

Hello!
They gave the site for revision.
There are only HTML, CSS, JS files.
If I want to work with the GULP collector, I want to use SASS and PUG in my work, then what is the easiest way to do this? Those. you need to convert the existing site to PUG SASS. Use an online converter from HTML to PUG and from CSS to SASS? Or some plugins...