Check user is in User Group / Custom User Permissions
I believe what you're looking for is 'isInGroup'

{% if currentUser.isInGroup('groupHandle') %}


It will also accept an actual group object or a group ID as well.

There is also getGroups:

{{ currentUser.getGroups() }}


Will return an array of UserGroupModels all of the groups the user belongs to.

And finally, can:

{{ currentUser.can('permissionName') }}


Will check if the current user has the given permissions, whether that was indirectly assigned to them in a group, or directly assigned to them as a user.