I have a 13 Pro Max, and an 11. There is far more apparent lens flare AND glare with the 13 vs the 11 as the cameras and lenses are more prominent. I shot a short film for my cinematography class at Harvard over the weekend, and as an exercise to show how far smartphones have come, were were instructed to only use our phones. I shot with both phones, and the 13 Pro Max had MUCH more lens flare. BUT the shots taken with the 13 were FANTASTIC and very clear (when I changed the angle to remove the lens flare).
Reduce some of the glare & reflected light, and you'll get the shots you want. My film professor recommended a LENS HOOD. That is what professionals use to help solve the problem. And yes they do sell iPhone lens hoods - you can Google it. I tried to post some lens hoods with good reviews but it won’t let me as it’s flagged as advertising.
Also - here is a link to 60 seconds of the short that I shot with my iPhone 13 Pro Max at WaterFire Providence. I think the low light shots came out GREAT - check it out for yourself!
Link to short - shot with 13 Pro Max:
https://vimeo.com/manage/videos/625422537
Good luck!
-Frank G