Sgt.HoundDog
What scale is that? Those figures are perfect.
Everything is 1/72nd (allegedly). Brands do vary, but you can't be choosey given the shortage of ground crew figures. In those builds i have used figures from 3 or 4 different brands.
If your useing figures from different brands, thats when issues can arise with size. Airfix figures for example are closer to 1/76. Of course real people vary in size, but as mentioned above, in this scale it would be tiny. So placement is important. I won't put a standing Airfix figure next to a Revell one for example, but a kneeling Airfix figure will be fine.
Just position your figures around the scene and adjust them until it looks right.