I have two email addresses associated with my account that I can send from but there isn’t an option to pick one when I send from my phone.
I have two email addresses I can send from on my account, my regular work email and another one that’s specifically the domain of the client I manage. On my laptop I can select the one I want recipients to receive from. I cannot do this on my iPhone. Additionally I would love to customize out of offices to come from the email address specifically that people are reaching out too.