Settings for uploading the clearest (and quickest) image on a website

What settings are the clearest and quickest to load for images? I am trying to export plans from adobe Illustrator. So far I export it as "save for web (legacy)’ and then PNG 24. It comes out pixely. Any tips?

Wix Editor

SVG → no pixely anymore.

Hi, Yes! I did svg and compressed it to be below 250 kb. But in the end I kept it as a pdf and used a pdf view widget on Wix instead!