If I understood you correctly, then Berkeley-style Idealists would be an example. However, I have a strong suspicion that I’ve misunderstood you, so there’s that...
Solipsists, by some meanings of “out there”. More generally, skeptics. Various strong forms of relativism, though you might have to give them an inappropriately modernist interpretation to draw that out. My mother-in-law.
Who thinks that there isn’t something out there which our ideas can model?
If I understood you correctly, then Berkeley-style Idealists would be an example. However, I have a strong suspicion that I’ve misunderstood you, so there’s that...
Solipsists, by some meanings of “out there”. More generally, skeptics. Various strong forms of relativism, though you might have to give them an inappropriately modernist interpretation to draw that out. My mother-in-law.