To get Precision Charge Mods in Destiny 2, you will need to visit Banshee-44 and purchase it from him. But, to get the mod from Banshee-44, you will need to have a total of 10 mod components.
If you don't have the required amount of components, you will need to complete a few bounties offered by Banshee-44. These bounties will require you to complete various tasks that range from killing enemies in a certain way, use of abilities, or using a specific weapon.
Related: Changes coming to Destiny 2’s economy in The Witch Queen
Complete these bounties, and you will get a small number of components each time, so farm these bounties until you can buy Precision Charge Mods in Destiny 2.
Once you have enough mod components, make your way to the starting area in the Tower and find Banshee-44. Speak to Banshee-44 and check if he has the mods in stock. If he doesn't have the Charge mods, you may need to wait until his inventory resets as he doesn't always carry the mods.
That said, if you manage to get a Precision Charge mod, you will be able to use it to become charged with light by using Scout Rifles, Hand Cannons, and Bows.
For more Destiny 2 guides, check out How to stack bounties in preparation for The Witch Queen in Destiny 2 right here on Pro Game Guides.