It is possible to set the default in the ACP but uses can override it in their settings.
Restrict User Search Access to Specific Group
We've set up a Category for a specific group of people that aren't related to the rest of the users using our forum. We'd like for them to see/search for users only in their Category's group. Is there a way to allow for a user in a group to only be able to search for people within their own group?
It is possible on the group page itself, for example if you search users on https://community.nodebb.org/groups/gamers it will only search that groups members. The front end doesn't have that option on /search though.