I’m not in the area generally as an exiled Devonian now but some stuff I know of…
Trail centre – Haldon. The official stuff is a bit “meh”. Not bad, but the red is just over too quick, the “black” is a joke, and the blue is more of a family trail (though if you can get a run of it when no families are on it, it’s a fast blast). There’s some nice off piste though off the cafe side that makes it more worth a trip.
DH – Gawton near Tavistock. Not been but from everything I’ve seen it looks proper serious stuff. Uplift too.
There’s Woodbury Common over by Exmouth. Need to explore, have a guide or look up routes but a fair bit around there. MoD land so watch out for the marines and keep out of their way.
There’s Keypitts/North Devon Trails, not too sure what kind of stuff. Pay to ride I believe.
Cann Woods is a local Plymouth spot. There’s Plymbridge trails as a recent build also but I believe it’s little more than a family trail and it keeps getting sabotaged by nimbys.