Basement has an exiting dry wall ceiling. The ceiling is textured. Walls are still cinder block. I am wanting to frame the walls then dry wall. Questioning what my approach should be to preserve ceiling .

Not sure how much detail you are asking for but I would double the bottom plate.
Nail or screw a 2x4 to the floor where you want the wall to be. Measure from that plate to the ceiling and build your wall to that height. That will allow you to stand the wall up and put it in place with out marring the ceiling.
Of course you could do the same thing by doubling the top plate but that would probably require some assistance in nailing a 2x4 to the ceiling.

Using the double plate on top will give u better nailing for cove or crown molding.

If u tape and compound walls to ceiling, the chances of matching texture are slim. Each hand has a different effect.

U can use a ''dead man'' (studs to hold up top plate up) until plate is nailed.

Chuck