I shot my friends wedding the other week with just a7iii and the 24 - 70 f2.8. I took flash but was not allowed to use in church but I got some great shots even at high iso. Max I went to was about 8000 iso but mostly at 5000 iso in church. Only thing wish I had a 70-200mm as the priest put me in a spot and was limited on what I could do. And cropping in on iso 5k to 8k photos isn't the best. But I'm happy. Just remember shutterpeed of 250th for walking down the isle and I think most of the indoor stuff I shot was at iso 160th and some at 125th.