It's typical to omit locking while the transmission is cold, some transmissions may not lock the first gear, or may not lock at lower revs, or at slower speeds,

It's typical to omit locking while the transmission is cold, some transmissions may not lock the first gear, or may not lock at lower revs, or at slower speeds, but generally the lock is there and it's just software that controls locking. You can rather safely assume that on most modern cars and in general conditions the torque converter will lock starting from the first gear.