I don't think that's possible at the moment (record types are not marked as such, they are just regular types).
Tagging @agocke @CyrusNajmabadi for thought

Note: this should not block 16.7p3 release of records preview, in my opinion.

Tentatively, we could use the unspeakable clone method (<>Clone) as a way to detect record type.

Note: for init-only properties, we've already fixed MetadataAsSource to print out init; accessors.

Relates to #40726 (test plan for "records")