Recording at Event with iPhone 14 with XLR audio

A condenser microphone requires power to operate. Most condenser mics have the ability to switch between an internal battery or phantom power provided by a mixing board or mic preamp.

First, find out if your microphone is a condenser type. If it is, see if it has a compartment for a battery. If it does, insert the required battery type. If it doesn't have a spot for a battery and it is a condenser mic, you will need to put a portable mixer or preamp that supplies phantom power, in line between the mic and your phone.

I looked on Amazon and they have several XLR to Lightning cables. You might have a look at those since they don't require any adapters and are made specifically for this purpose.

Do a search for XLR to Lightning cable. Or if the microphone receiver has a line out jack, search for audio line out to Lightning cable.

No, not a power issue if they are wireless. You're just going to have to experiment.

Yes, not all mixers have the phantom power option, but usually the higher end ones do.