International flight with domestic layover quarantine


I live in El Paso. My family will visit El Paso in May from Japan.

Their flight is from Narita Airport to Dallas Texas (DFW) and then El Paso. Layover in Dallas for 4 hours.

I know they have to do COVID test before their flight.

I was wondering if they have to quarantine in Dallas? or they have to quarantine after they arrived El Paso?

Or they dont have to do it if the COVID test is negative?