iOS users can also make use of the Gmail app for sending messages and attachments. The official Gmail app brings the best of Gmail to your iPhone or iPad with real-time notifications, multiple account support and searches that works across all your mail. One thing which is new is that Gmail for iOS now supports adding attachments from the Files app. This is a feature which was already available for Android users.
That said, it implies when composing or replying to an email, iOS users can now upload attachments from the Files app on their iPhone or iPad.
Based on the information from the Gsuite updates blog, this feature will be available by default.
In the Gmail iOS app, when composing or replying to an email, click the attachment icon and scroll to the “Attachments” section. Then select the folder icon to select an attachment from the Files app.
Gmail for iOS attachments from the Files app feature rollout
This feature started rolling out a couple of days now. The rollout process for iOS users started on February 12. And it may take 15 days or more for the feature to arrive everyone.