@Lynn61: Can you try heading to the Gmail app > Tap the 3 lines in the top left > Settings > General Settings > Hide bottom navigation on scroll > Off > Auto-fit messages > Toggle this off, then on again. If the problem persists then close the app and head to Settings > Display > Font size and style > Font size, and move the slider to the left > Back > Full screen apps > Gmail, and toggle this on.
If you're still experiencing issues, please can you confirm if the problem is present for all emails, or just certain ones, as it may be a formatting issue from the senders side?
Zooming out is not the problem, that doesn't help me see the righthand side of the email
The font size is default but I've also tried setting it to the smallest and it makes no difference