I always charge my phone on a MagSafe stand at night - NEVER with a cable. I truly believe that this leads to having the best health. I also noticed this with my previous iPhone.
Launch day iPhone 15 Pro, 96%, 304 cycles. My battery was 100% until I took a 3,000 mile road trip in July. My phone was connected to wired CarPlay running Apple Maps and Audible the whole time I was driving, and at the end of the trip my battery capacity was down to 97%.
Launch day 15 pro max just dropped to 92% battery health as we officially near the 1 year mark Sept 22. I think it will last until Fall 2025 when I upgrade to the 17 pro max.