NeoCities supports basic HTML pages, but I'm pretty sure if you want anything fancier you have to BYOF. I've seen a lot of NC users whose stuff is built on static site generators, at which point we've wound back up at the terminal (and frankly I'm not sure why you need NeoCities at that point anyway when Netlify et al. already offer free tiers).
https://gilest.org/indie-easy-again.html