Shared Wisdom in Destiny 2 is nothing but asmall XP boostthat your entire fireteam receives while playing together. There isn’t any special way to activate it. The Shared Wisdom XP boost applies automaticallyto all your fireteam members the moment you queue for an activity together.
However, in order to activate this Shared Wisdom XP boost, you need to unlock it first. In order to unlock this boost, you will have topurchase the season passin Destiny 2. The XP boost you receive will depend upon the Guardian with thehighest Shared Wisdom unlocked.

Related:How to complete the Gift of Appreciation quest in Destiny 2
For example, if you’re in a fireteam where one Guardian has a 6% boost, another Guardian has 12% boost and you have a 4% boost, the total XP boost you will receive will be 12%.
This Shared Wisdom XP boost can be unlocked at different tiers of your season pass. The tiers are as follows:
Tier Unlocks
Also, check outHow to unlock Deepsight Tier 2 & 3 in Destiny 2only on Pro Game Guides.