As the title states, how do I get the closest pawn to the AI using EQS for a multiplayer game?
The EQS documentation shows how to set up environment queries:
https://docs.unrealengine.com/en-us/Engine/AI/EnvironmentQuerySystem/QuickStart
, create a context that finds all the actors of your pawn class.
Then you just need an environment query that generates a simple grid around the querier and has a Distance filter that checks for the distance to your closest pawn context.