They’re easy to find, use 571 as well as 650c for search terms, and remember that the big online shops list tyres by model, not size, and that model might come in 700x20/23/25/28 & 650x23…
But for wider 650C you’re generally out of luck, I think that Bontrager is no longer made, which leaves the 24mm Conti and the 28mm Terry. I’d go the 28mm if the frame/brakes clear. Smaller wheels & skinnier tyres isn’t much fun unless you’re a speedo-bro.