To really change the scale, as you say, you would need to scale up the obj file. That's not hard, but then all the joint parameters would be out. You would need to more or less completely re-rig the figure and that would be a very big job.

If you just want the scale dial to read "100" as default, that's probably quite easy.

If this is one of the DAZ figures like V3 that use channels named "PBMDC_01" e.t.c. Then I could probably make a pose file to do it. If not there are other ways. Let me know and I will get back to you.