Yes, the TV automatically switches between SDR and HDR when I toggle the option in i.e. TLOU or Uncharted 4. Can also be confirmed in the action menu. Not sure about your model tho, there should be a way.
It's also easily apparent when looking at the game itself of course (Bright highlights and all that jazz).
Ah cool. Just realized I have ratchet and clank to test, and yeah definitely can tell it isn't enabled on HDMI 1 despite being enabled in the PS4 settings, but can tell it's enabled on HDMI 4.