Dynamic Signature

I would like the Email Signature to have more dynamic fields available. In particular, to be able to customise the signature to match the From email that the Public comment is being sent as.

If I have two custom domains, helpdesk@brand1.com and helpdesk@brand2.com, the email signature template either needs to have dynamic fields that can change the Brand name, or possibly something like Gsuite does, where you can create multiple signatures and assign them to different From addresses.