Expert Archer

Long training with bows and other ranged weapons has enabled you to line up the perfect shot and so to improve your chances of scoring a critical hit. You gain the following benefits:

Ability Score Increase: Increase your Dexterity score by 1, to a maximum of 20.

Steady Focus: You can give yourself a sniper's focus. Until the end of the current turn, your speed is 0, and your critical hit range for ranged attacks increases by 1 (typically, from a 20 to a 19 or 20). You can't use this benefit if you've moved this turn. You may ‘buy back’ your movement after your ranged attacks at the cost of your bonus action that round, if you so choose.

Note that the archery fighting style is a prerequisite for this feat. (If you chose a different fighting style earlier, taking this feat allows you to swap out that fighting style for the archery style.)

Also, note that the Master Bowman feat is the next step in this ‘feat chain,’ and that it removes the movement penalty, enabling one to have Steady Focus while taking normal movement.