Not in the UI, I was going to make a PR for this, but what I do :
Insert the catchall inside of cyberpanel’s e_forwardings table using phpmyadmin ( like source= @example.com with destination= [email protected], you’ll have to create a destination mailbox btw )
Then replace query in /etc/postfix/mysql-virtual_forwardings.cf with
query = SELECT DISTINCT destination FROM e_forwardings WHERE source='%s' OR source='@%d'
And that’s it. I do it like that because for some domain I don’t even want to create a mailbox and just forward all emails to gmail.