Theres a fun moment in Weregeld, one of the novellas in Corax (the Horus Heresy book 40) where the titular primarch realizes how baseline humans must feel when he shows up and needs to enter rooms and also sometimes sit
It doesnt elaborate much but its the closest I've seen in the series of the primarchs being aware of how huge they are. Of course, there are frequent mentions of them having their own big chairs in their own big buildings brought down from orbit, and the novels that show Guilliman on Macragge tend to mention that his office area has furnishings in three different scales to accommodate humans, astartes, and himself. Also whenever one scale of guy has to enter the quarters/cell/etc of a smaller scale guy theres usually comments about that space being very crowded. But the big guys themselves seem to lack an awareness of their bigness
I haven't seen primarchs get embarrassed by baselines having to frantically rearrange a room so they'll fit but I imagine that's happened loads of times for most of them. That or they've been keeping to areas set up specifically to accommodate their scale (when not genociding uncooperative baselines i mean). Battle barges are built big for the astartes and a few extra feet in height to doorways and ceilings isn't much additional effort.
That and apparently every single structure in the galaxy is designed to withstand several thousand pounds of weight bc I would expect a lot more power armored transhumans to fall through floors otherwise. In the other novella in this same book, Ravenlord, Corax is flying around a mechanicum town and lands on a metal walkway and the entire thing does NOT collapse under him. Nor does the decorative molding around windows that he clings to while eavesdropping.
