It's an absolutely key technique of modern red winemaking. Toying with tannins There are several ways you can do this. New oak barrels help to polymerize tannins. Oak chips have the same effect - you dunk them in fermenting wine like a great big teabag. Even makers of fine wines use them, because they're important to the structure of the wine.
Tannins also taste richer and softer if they're riper in the first place.
That's a very important tip that Europe learned from warmer climates like Australia and California, where it's much easier to get grapes really ripe. In cooler climates you need to leave the grapes on the vine for much longer. That means the structure of the wine can be the same as that of a ripe New World example. So, although the classic winemakers of places like Bordeaux, Piedmont and Tuscany shudder to hear it said, because of the New World example, fine young reds now can have it all. They can be gorgeous in barrel, gorgeous just bottled or two years further on.