Aircraft smooth return to level flight after banking...

I have an aircraft and, via joystick input, I Roll to the right which indices a yaw/turn to the right. But when I release the joystick, the roll stops as expected) but the aircraft should keep on yawing/turning to the right (relative to the amount of roll). The Roll should also diminish over time and eventually return back to level flight.

Can anybody point me in the right direction (no pun intended) code wise on how to handle this?

Quaternion.Slerp() might achieve a look similar to what you want. It’ll take one rotation (eg, current rotation due to roll) and interpolate it to another rotation (eg, current rotation with no roll).