Namelama

Very appreciative of any direction on this subject. Purchased an 8 channel 4K Dome camera system with a DVR which accepts RJ45 fittings (CAT5+ cable) Our dilemma is the third party contractor for the builder ran BNC bulk cabling for 4 cameras and we ran 4 CAT6 cable. Can we convert the BNC bulk cable to RJ45 fittings and have similar performance using the Costco purchased LOREX 4K system using Baluns or some other type conversion fittings?