2020 explorer will not fill up

Are you sure the gas station was open? I recently had the same problem and found that the lights were fully on at the station, the digital readouts on the pumps were glowing, but the place was actually closed and the station owner disabled the pumps. Many stations are closing earlier than expected due to COVID-19. If you are using a credit card to pay at the pump, make sure its authorization wasn't rejected.

Did you try a different pump, or perhaps a different gas station altogether? I've ocasssionally had weird back pressure on a filling nozzle.

Your Explorer has a "capless" filling system. Be sure you are inserting the gas nozzle fully, because it must get past two, spring-loaded rubber flaps inside the neck of your gas tank. See this video from Ford for a further explanation. Also, try changing the angle of the nozzle a bit, re-inserting it up or down, and try to fill again.

If this really is a brand new vehicle, why not take it to a Ford dealership under warranty? There really shouldn't be anything else for you to do.