Look, I have shot in those old Italian chapels and they are basically caves. I would be very careful about relying on f4 for a wedding ceremony. While the R5 Mark II is a beast with high ISO, you dont want to be pushing 12800 just to get a decent exposure. It can get messy fast. Heres how I see your options based on my time with the R system:

• Canon RF 24-70mm f/2.8L IS USM: This is the safe bet. f2.8 gives you that vital extra stop of light over the f4 which is massive when the sun goes down. The reach is fine, and honestly, you can just crop in a bit with those 45 megapixels if you need more zoom. Its a total workhorse.
• Canon RF 24-105mm f/4L IS USM: The extra reach is tempting for outdoor portraits, but i would suggest avoiding it for the actual ceremony. You might find yourself struggling with grainy shadows. Its a great travel lens, but maybe not for a high-stakes indoor event.
• Canon RF 28-70mm f/2L USM: If you can handle the weight and price, this is the king. It basically replaces a bag of primes. Be warned tho, its heavy and might kill your wrist by the reception. I would suggest getting the 24-70mm f2.8. Just make sure to double check your eye-tracking settings before the big day because that camera has a lot of new tech to learn...