You can call Work-Relay Action/Action Group as a handler in Einstein Bots. 

• Create new Action or Action group.
• See more info on creating actions in Actions/Action Group Basics articles.
• Add new Action with type Apex to your Bot.
• Select "Execute Work-Relay Action" Action in the Actions picklist.
• The Action/Group ID or Name (String) - fill in with the ID or Name of required Action.
• The Source Record ID (String) - pass Source record ID.
• The Initial Variables (String) - pass variables to you Action in JSON format.

You can retrieve up to 5 variables from your action/action group. 

Assign variable to the each of the outputs.