Asuming your driving line through the corner is correct.

Change only one setting at a time in small increments

From more to less influence

• Decrease front ride height
• Increase rear ride height
• Increase front splitter angle
• Decrease rear wing angle
• Decrease front spring stiffness
• Decrease front anti-rollbar stiffness
• Decrease front negative camber
• Decrease rear negative camber
• Increase rear spring stiffness
• Increase rear anti-rollbar stiffness
• Decrease rear tyre toe-in
• Increase front tyre toe-out

Having the weight over the front tyres will generally always help with understeer and in the middle of the corner, when the car is transitioning into accelerating you need to keep it over the front tyres which can be achieved by increasing the rake, or stiffening the rear suspension.

Additionally slightly softer front suspension can help with the grip on the front as well.

Additionally in high speed corners, aero changes will also have a big affect on the balance of the car through the corner, as well as decreasing rear tyre toe-in will induce a bit more instability of the rear of the car and help with turn-in.