You can enable our exit intent pop-up for the cart page by going to Setup > Incentive Configuration and scrolling down to Step 2 - Cart page options where you can select to have this feature enabled for the Desktop and Mobile. The pop-up would be activated once the customer's mouse cursor goes past a certain point on their browser, which indicates that they are leaving.
For the Mobile option, it will be a timed pop-up, for which the time delay can be set in Look & Feel tab.
