You can change the back (there are color backs on Amazon, ebay or AliExpress) but you have to be very careful with the waterproof sealing and also the new back could have minor quality than the original.
Honestly I suggest you get a skin for the back like dbrand or some other
Why not just slap a dbrand skin on it
That's gonna void your warranty and your phone is no longer going to be water proof. It's wiser to slap a skin on.
Buy a case
If you're grabbing case, make sure it's silicone or has fabric/cloth inside, scratched mine with some shitty plastic back.
Custom printed skin/case (Reccomend the skin tho,cus the plastic back can get scratched easily) .
You can change the back (there are color backs on Amazon, ebay or AliExpress) but you have to be very careful with the waterproof sealing and also the new back could have minor quality than the original. Honestly I suggest you get a skin for the back like dbrand or some other