Check the size, a decent size pic will be at least 3600x 2700 pixels and over 1MB. If you are on a proper computer, right click on the pic and select properties to check the size.
Note that when you send pics via Messenger and WhatsApp they will automatically reduce them. Email is best. Send as a separate attachment (not embedded in the email) and select "ACTUAL SIZE".
Some email apps automatically reduce attachments, Apple is worse for this as it dumbs everything down. You may need to alter your settings so you have an option. DO NOT SELECT SMALL, MEDIUM, OR LARGE, keep the image with the ACTUAL SIZE.
https://mrdif.com/how-to-send-photos-in ... on-iphone/
Many thanks
.