Thick hair gives a stylist plenty to work with, but it can also hold weight in places you do not want it. The goal is not to remove as much hair as possible; it is to decide where fullness supports the shape and where it gets in the way.
Bulk and density are not problems to erase
Internal layering, graduation and selective weight removal can make a cut move more easily while keeping the outer shape strong. Over-thinning can create short pieces that expand, frizz or make the ends feel unexpectedly light.
Choose the silhouette first
A bob can use thickness to create a strong perimeter. A shag can distribute that weight through layers. A pixie can feel much lighter overall, but the crown and sides still need careful control.
Ask how the cut will behave at home
If your hair expands when air-dried or becomes much smoother with heat, say so before the cut. The same shape can behave very differently depending on your normal drying method.