Unlocked iPhone 13 or newer (Downtown Wellsville, NY)

I currently have an iPhone 12 with 256 GB. However it is starting to show signs of dying. It overheats when charging or playing mobile games. It is starting to lag, even when connected to WiFi. The screen will randomly flicker, or dim (auto brightness is turned off and the brightness setting will be unchanged). If anyone can help me out, I would greatly appreciate it.