Duplicate homepage completely with template?

Site URL: https://imnotascientist.com

I want to make three identical versions of my site, but with completely different aesthetic themes.

I currently have this windows 98 theme, and I want to do a minimalist one and one more.

I know I can duplicate every single page and re-design them, but I can't seem to duplicate the main template homepage in the screenshot here. There's no option in settings. Is this possible?

Also, right now I have a site-wide background color, and injected some code to add icons to the nav links. I'm not sure how I'd be able to do that all in my same one URL domain, is it even possible or would it take like some serious coding?