QUICK FIX: If you want to hit your irons further and crisper, then right-handed golfers should stop trying to keep their left arm straight. An incorrect grip will result in loss of power.
If you would like to hit the ball further and crisper with your irons, you need to have the ability to hinge your wrists to generate power. Let's start with the grip.
The way we hold the club is hugely important. The hands control the clubface and if they are incorrect on the grip, then the clubface will not be on target at impact.
A quick check would be to support the club in your left hand using only the fleshy pad and the index finger. Your right hand you have the 'V' pointing parallel with the left. Grip pressure should be like holding a tube of toothpaste with the lid off!