Hi Jack and welcome. Yes, this model has a 24" Cold Hammer Forged Barrel with a 1:11 Twist Rate and
5/8"-24 TPI Threaded Muzzle. Cheers and stay safe!

Yes. It is threaded. Here's the specs.
Tikka
T3x UPR
CALIBER
308 WIN
RECEIVER SIZE
T3x
HANDEDNESS
Right
WEIGHT
7.9 lbs
Total length40 in
Barrel length20 in
Rate of twist1:11"
Magazine capacity10 + 1
TriggerSingle Stage Trigger
Picatinny rail0MOA
MaterialBlack Steel
Stock materialGlass fiber
Stock finishDesert Sand
Muzzle thread5/8-24
Cheek pieceAdjustable
Open sightsNo
Changeable gripNo
Folding stockNo
Fluted boltNo
Fluted barrelNo