Hey @JackBeStupid!
In your character blueprint, navigate to the Components window at the top left and click on the character movement component. While having it selected, navigate to the Details window on the right side, type in “rotation rate” into the search bar like this:
And adjust the Z component of the property to your liking 
Check out this tutorial on adding leaning to the character:
To create left and right leaning animations for you character, duplicate your animation sequence for moving forward, open up the duplicate asset, navigate to the Skeleton Tree window on the top left, click on a bone you wanna adjust, hit E on your keyboard and rotate it slightly to one side, and hit the Key button at the top with a plus (+) icon next to it to add the bone transform to the Additive Layer Track. Do the same for the other side as well, by creating another duplicate of the original animation sequence, and use these new left and right leaning animations for your leaning mechanic 
Hope these help!