We are wondering if we have to change the coordinates on the field depending on our alliance color to retrieve correct poses. Additionally if we do have to change the coordinates, how would we do that?
You shouldn’t, no. The tags on opposing sides of the field are numbered differently. In fact, every AprilTag on the field will have a unique ID number
The field is symmetric about the centerline, and its length (x axis) is 16.54 meters. If you’re relying on field coordinates and you’re using meters, the conversion from one alliance to the other is x = 16.54 - x. (No conversion for y.)