My friend had his 2019 Charger at dealership under warranty for transmission issue for over three months, baking in the Sun. I told him he's crazy not DEMAND a loaner/rental vehicle. He was also told parts were the problem.
Anyway, he finally demanded a loaner and got one. He has another car but I'd still demand one; then at least you're saving mileage on your own vehicles AND they are less likely to put you on back burner.
If it makes anyone feel better, our Phord Exploders ROUTINELY spend months at dealership; "parts on order". One just came back after four months, and the windshield was cracked (their issue) so it had to wait on that "on order" and go back to dealership for replacement.