The best way to scale a 3D model with supports is to use a 3D printing slicer (like Cura or PrusaSlicer) for uniform scaling—this ensures supports adjust proportionally, keeping the model stable during printing.
Uniform scaling prevents supports from being too thin (weak) or thick (wasteful), as non-uniform scaling misaligns them with overhangs or delicate parts. Most slicers update supports automatically when scaling, but always check if they still anchor overhangs or fragile features correctly.
After scaling, preview the model in the slicer. If supports no longer contact the build plate or overhangs, tweak their density or distance slightly to maintain structural integrity.