Although hitting 0.2 implies more treatment is needed, it doesn't necessarily happen immediately.
Some times, they wait until you get to 0.5 so they can do a scan to locate the cancer before starting treatment, although the newest PSMA PET scanners can work down to 0.2.
Some times, they will assume the recurrence is in the prostate bed due to the pattern of PSA rising or the histology of the removed prostate, and treat without waiting for a scan.
You might be given the option. I would certainly ask about having a PSMA PET scan - this is more likely to happen if your hospital has that capability than if they have to send you somewhere else to have it done.