I phone 11 getting hot

Depending on what you are doing, and iPhone will get warm, or slightly hot. This is the processor, or sometimes when charging, and it is the battery getting warm from charging. If it is use, it can be if you are using something processor intensive, such as gaming, video, FaceTime calls on cellular and you have a poor cellular connection. A case on the iPhone can make it worse, as the outside case of the iPhone is how it dissipates heat. A case will hold that heat into the device. It is not abnormal unless it is so hot you cannot touch it.