In the Commodore 128, the Video Display Controller (VDC) was used for the 80-column mode. Two variants of the VDC were used, the 8563 and the 8568.
Looking at the POKEs, the address 54784 ($D600) is the index register for the VDC, while 54785 ($D601) is the data register.
So those two POKEs write the value 232 ($E8) to register 9 of the VDC.
Register 9 is ...