Oh man, you are going to have an amazing time at Zion! Its literally one of the most beautiful places on earth and your Canon RP is a fantastic choice for those trails. Since you are on a budget but want professional results, I have a few methodical recommendations based on my own kit. I always tell people to stick with native RF glass because it is the safest way to ensure your autofocus stays snappy and you dont have any weird mounting issues while out in the wilderness.

• Canon RF 16mm f/2.8 STM: This is the absolute best for those massive mountain vistas. Its super wide so you can get everything in one frame without having to stitch photos later. Its also incredibly light which is huge if you are hiking Angels Landing or The Narrows!
• Canon RF 24-105mm f/4-7.1 IS STM: If you want something more versatile, this is the safest bet for a one-lens setup. It covers wide angles but lets you zoom in on specific peaks too. Basically, native lenses are way better than messing with adapters when you are starting out. You dont want to deal with potential communication errors between the lens and camera while you are in the middle of a national park. Also, grab a Hoya 43mm NXT Plus Circular Polarizer to make those Zion skies look incredible. Honestly, that 16mm is such a win for under 300 bucks... you really cant beat it!