I've got a 2018 with stock 6 speaker system and 8.4" screen. To get more bass in my truck I went with a powered, compact subwoofer (like what SilverBullet85 suggested.) They are designed to fit under the seat (usually the back seat, but could be the passenger front seat) or behind the back seat. They are maybe 13" X 10" X 3" (very slim) and have an amplifier built into them. They don't require any structural changes to your truck, that is, you won't be building custom box enclosures or adding power amps.
I got the Rockville USS8, an 8" powered subwoofer and stuck it behind the back seat of my Big Horn. With the added space in the back seat of the 2019's you could probably get a 10" powered sub to fit on the floor behind the seat.
Here are some brands/models you could investigate:
Rockville USS8 or USS10
Cerwin Vega VPAS10
Kicker Hideway
Maybe take a look on Amazon.
Besides a subwoofer your next move should be to replace the corner dash speakers. At a minimum a powered subwoofer and corner dash speakers--that would be my two moves.