Using the same fill you can use 2 different pen sets for the drawings. One for the floor plan were the fill pens are grey and one for the sections were the same pens are white.
Eduardo Rolón AIA NCARB AC27 US/INT -> AC08
Macbook Pro M1 Max 64GB ram, OS X 10.XX latest another Moderator
You can also use "Uniform pens for cut elements" in Section settings and show your fills as white, or use Model View Options to set different display options.