Like kayn1 said, there are no standard offsets for PLMRS VHF frequencies.
Looking at Clayton County's WQPZ502 license, there are two repeaters (151.130 and 156.2175) and two frequencies licensed as FX1 (control stations), which would be the inputs to those repeaters, 153.875 or 158.940.
It's also worth noting that the county has an application pending to add MOTOTRBO emissions to all frequencies on that license.