The Inquiry class was a Starfleet heavy cruiser of the late 2390s, making up the fleet that William Riker led to the planet Coppelius in 2399 to face the Romulans.
The class appears in the Picard first-season finale, Et in Arcadia Ego, Part 2. As a Romulan fleet under Commodore Oh prepares to wipe out the synthetic community on Coppelius, a large Starfleet force drops out of warp to protect the planet, which Picard has asked the Federation to recognise.
Riker, temporarily back in uniform, commands from the USS Zheng He and describes his ships to Oh as the toughest and fastest Starfleet has ever put into service. The two fleets face each other until the synths shut down their beacon and Oh withdraws.
All of the Starfleet ships in the scene are of the one design, with a broad arrowhead saucer, a slim secondary hull and nacelles on swept pylons.