Probably a mix. Has the look of a roller, except they don't have crests. Some highfliers have crests, but it doesn't yell "I'm a highflier" either. So I vote a mix
It's a pretty little bird though, and looks quite clean and healthy. Probably JUST got lost before it found your cousin's house as a safe haven. Also looks like it enjoys hanging around the pool
It will probably continue to hang around her house until she or someone can catch it. Best time to catch it is at night, once you find out where it roosts. If not, the box trap works pretty good too Tie a string to a stick, prop the box up with the stick, and put some seed underneath it.
Then once it is caught, you can check it over to make sure it really is okay, and either keep it as a pet, or put it up for adoption
But of course you could continue to let it stay out there, but then it's in danger of owls, hawks, and other predators