I just tried modeling a PtP 450b 5.4 DFS link and it appears that it sets the TX power and EIRP correctly. No need for any manual user input. Any Cambium radios with an integrated dish set to the United States region are going to have their antenna gain fixed and the EIRP will adhere to the band being used, so there’s no way for you to increase the power beyond the allowed EIRP. The only way to do that would be to use connectorized radios and fudge the antenna gain field.
Cambium has a good KB article regarding PMP450 and 5.4 here you can reference: