Why My phone Getting hot while charging even using

Hello Someone answer me speacially apple company please I'm still confusing I buy iphone 13 last two weeks and I notice that when I'm charging its getting hot or warm then when he reach at 80% gets cooling down its theres any problem in my iphone?? Also When I ussing I experience getting hot or warm but my concern is While Charging its getting hot please Reply me about this atleast i will not confuse or thinking to return if this normal only for iphone by the way this is my first Time using Iphone or Ios but Now I'm getting Dissapointed if this is problem or normal only