It is getting easier again. Google Flights gives indications on each leg whether it is roomy, average, or tight. For premium classes, it reports recliner, ang

It is getting easier again. Google Flights gives indications on each leg whether it is roomy, average, or tight. For premium classes, it reports recliner, angle-flat, or lie-flat. You still can't search by it, though. This isn't much, but it is integrated into a flight search engine. Of course, if you really want to know, there are sites like seatguru with all the details (but average travelers are never going to look for that)