In case anyone is wondering, on a Sora 9-speed derailleur, you can fit a 42 tooth sprocket and a 11-42 cassette with no issues. Shown on a 2016 Trek Crossrip Elite. : r/gravelcycling
Campagnolo Record 10 Speed Rear Derailleur TotalCycling.com
Ensemble de vitesses pour vtt 1x9 vitesses, dérailleur arrière 9 s 11-36/40/42T, Cassette