No, a better trigger action does not enhance the inherent accuracy of the rifle. But it can sure help many of us to shoot a rifle more accurately.
Theoretically, one can shoot a rifle with a heavy, gritty trigger pull as accurately as one can shoot the same rifle with a light, smooth trigger with a crisp break. But the chances of pulling the sights off target are much greater with the poor trigger.
To maintain the same degree of accuracy with that heavy, gritty trigger requires two qualities that many of us do not have. First, if using iron sights one has to have good visual acuity to ascertain that the sights are remaining precisely aligned and on target. Second, one has to have excellent trigger control and technique.
Even Hickok45, who has shot a heck of a lot of pistols and rifles with far greater accuracy than I ever will, says that the firearm characteristic that has the greatest influence on his accuracy is trigger quality.