There are several ways you could do this, one of which is through the Ease function. There is also Lerp, and FInterp, each which have slight variations in how they work or how they ease, and all that comes down to personal preference for your use case. So I’m going to show you FInterp.
Essentially, you’ll want to set your rotation speed each tick that the player is holding down a key to turn. Whenever the player lets go of the key, you can reset to 0 or ease back down, your choice. Set up a Max Rotation Speed variable as the target. Delta Time you get from the Tick Function. Play around with Interp Speed to find a value that speeds up correctly; I’d start with an InterpSpeed of 5 and go up or down from there.
