This Unreal 5.3 Gameplay Ability System video is about adding a set of Firing Rate Upgrade Cards. This will also require some new functionality to allow setting a variable Cooldown Duration.
We start by adding the Firing Rate Card entries to the Enum, and then we update the Map variables in the Game Instance Blueprint. We then create the Gameplay Effects for Firing Rate Upgrade and Weapon Cooldown, and update the Weapon Fire Gameplay Ability logic to include using that Firing Rate value to apply the Weapon Cooldown Gameplay Effect, and later add it to Activation Blocked Tag. Next, the Award Upgrade function is updated to include the values for the Firing Rate Upgrades, and lastly, we show an extended example of Firing Rate change gameplay.
https://dev.epicgames.com/community/learning/tutorials/PnEL/unreal-engine-38-player-progression-upgrade-system-firing-rate-let-s-make-a-top-down-shooter