In addition to server-side bits like IP address, request headers and TLS/TCP fingerprints, there are some client-side things you can do such as with media queries, either via CSS styles or elements that support them directly like <picture>. You can get things like the installed fonts, screen size/type or platform/browser-specific identifiers.

https://fingerprint.com/blog/disabling-javascript-wont-stop-...

There is also a method of fingerprinting using the favicon: https://github.com/jonasstrehle/supercookie