Coming from a regional, you’re likely to be in a “light twin” class at UPS. At your age, you might squeak out a SDFZ assignment but SDF 757 or A300 is more likely. That means, at least for the first year or so, night sort flying. Right now, seniority for newbies is moving faster on the Boeing than the Bus for two reasons - 767 growth airframes and Bus undergoing avionics conversion for the next 15-18 or so months.
18 month newhire seat lock, but you can change domiciles on the same fleet. SDF 757 to SDFZ 757 will allow you the opportunity for international flying, but you’ll be more junior longer.
This job ain’t for everybody, but it is very very very good with career earnings potential value proposition favorable toward someone with only 19 years until mandatory retirement.
You have a good problem…