You can do it on Android.Open the email.Click the three dots up the top right of the mail (not the app) the dots are below the mail’s date.Click to print the email.When selecting printer, there should be a “Save as PDF option”.
How to Save a Microsoft Outlook Email as a PDF (Desktop and Mobile)
Easily save an Outlook email as a PDF on desktop and mobile. Here's how to convert an Outlook email into a PDF on Mac, Windows, and iPhone.