In my experience kingpins rarely just “fall out” after removing lock pin, usually involves a big hammer or hydraulic press. If it was a new axle or freshly rebuilt sure, they’d be easy to tap out or possibly push out with a thumb.
If you plan to remove the axle, do so, then do kingpins and bushings, easier off the truck I think. Though not necessary to remove if you don’t have plans otherwise to pull the axle, or if the pins come out easy.
Could start disassembly on the truck but if pins are real tight don’t get carried away with the big hammer and bend the axle, stop and use a press. Usually take the axle to the hydraulic press, though portable kingpin presses do exist.
