Leather and metal armors' information usually contains a line such as "Recovery Speed: -40%".

Is there a way to reduce or offset that effect? Does enchanting the armor with "Of Dexterity 2" help?

All speed modifiers in the game except Dexterity only affect the recovery time (or -speed - depends how you look at it).

Dexterity is the only thing that not only influences the recovery time but also the action (or animation) time.

So giving +2 DEX does indeed help a bit with the recovery malus of armor. Not much, but it helps. Note that attribute bonuses on items do NOT stack (except if it's on weapons or shields). So an armor with +2 DEX and a Ring with +2 DEX will NOT lead to +4 DEX.

The Fighter has a special ability called Armored Grace which does not influence the recovery time of the character directly but instead lowers the armor's recovery penalty.

Besides that there's dual wielding (+ Two Weapon Style), speed weapons (they carry an enchantment called "speed") and some other effects that reduce recovery time.

If you want to play around with those things a bit you can try out this tool: https://naijaro.github.io/poe-speed-calculator

THere you can try out DEX, speed items and -abilities with all armors and see what effect they have on your attack and recovery times (in frames).

There are also some consumable which help deny recovery, i.e. Potion of Power and Potion of Deleterious Alacrity of Motion and some eq, most of all Gauntlets of Swift Action.