Query state settable with select vt-xxx conformance level.
The terminal replies with
ESC1b P50 131 $24 r72 Ⓝlevel ;3b Ⓝ7bit ESC1b \5c
Where level is the vt level plus 60 (i.e. 64 for vt level 4) and 7bit is set to 1 if 7bit encoding of C1 controls is selected.