Will a battery replacement fix iPhone 15 Pro overheating issues?

If you’re using a laptop charger it’s definitely fast charging. The heat produced during a fast charge is normal and it’s the way charging a battery works. Your old cellphone probably didn’t have 5G and the downloading of data faster creates heat. Everything sounds pretty normal.

Make sure when charging and using your iPhone as a hotspot that you set it on a hard surface to allow for better dissipation of heat. In other words, don’t set it on something soft like a pillow, blanket etc. Soft items act as an insulator and the iPhone can’t release the heat it generates and the device gets warmer and warmer. Hard metal or glass surfaces are better conductors of heat and allow the iPhone to stay cooler.

Charging can make warm, especially if a fast charger is used. What wattage charger are you using? Using a hotspot will also make your iPhone warm. The modem will be doing double duty with both WiFi and cellular service. Scrolling shouldn’t cause too much heat, but excessive ads or videos can cause the processors to get warm.

Have you had your device examined by Apple?