Honestly, for Zion, you're gonna want that wide perspective. Those canyon walls are massive and if you go with the 28-75, you'll constantly be backing up into a cactus trying to fit it all in the frame. In my experience, the Tamron 17-28mm f/2.8 Di III RXD for Sony E is the absolute sweet spot for what you're doing. It's super lightweight which helps a ton when you're hiking up to Angels Landing or trekking through the Narrows. Quick tip for ya: when you're shooting landscapes, try to find something interesting in the foreground—like a cool rock or some brush—and get really close to it with that 17mm setting. It makes the scale of the mountains in the back look even more epic. Don't stress too much tho, the a7iv is a beast and will handle it. Just grab the 17-28 and enjoy the trip!

I had that same stress when I first started out. Just be careful tho, because wide angles can actually make mountains look really small and far away... its kinda counter-intuitive. You might want to consider the Tamron 28-200mm f/2.8-5.6 Di III RXD instead. It fits your budget and lets you zoom in to make those cliffs look huge. Plus, swapping lenses in the Zion dust is a total nightmare.

Unfortunately, I've had some bad luck with those standard zooms in the past. I tried out a 28-75mm on a trip last year and it just wasn't as good as I expected for big scenery... the corners were way too soft for my liking. It is a real bummer when you get back home and realize your shots aren't sharp. If you're heading to Zion, I'd look at the Tamron 17-50mm f/4 Di III VXD. It is kind of a letdown that it only goes to f/4, but for landscape stuff you're gonna be stopping down to f/8 or f/11 anyway to get everything in focus. I spent way too much money on fast glass years ago just to realize I never used those wide apertures for mountains. This gives you that ultra-wide 17mm for the canyon walls but still has some reach for details. It is not the most exciting lens, but it is practical and fits your budget.