You can send images and files with your emails. When you tap on the email button to create a new email, you can tap on the paper clip 📎 button at the top of the screen to add attachments.
If instead, you are viewing the advanced button view after tapping on the "..." button, then tap on the "+" button on the right of the Attachments area below the subject.

In the choose file/photo (Places) screen, you can add select one of the cloud server and file locations to view files. Tap on the circle to the left of each file and then tap on "Add" or just use the back arrow to add the selected files to your email.

To delete any attachments, tap on the circle to the left of each attachment to select it, then tap on the action menu button to the right and select "Delete". If there is only one attachment then you don't need to select it first, just tap on the action menu button.

You can use the "+" button in the top of the choose Places screen to add more cloud server accounts, eg Google Drive, OneDrive, DropBox etc. or WePrint for sharing your Mac or PC files. Choose the new cloud server type and enter your username etc. if required.
The "Files App" item will allow you to choose from the Apple Files App. Tap on "More Locations" in the Files App screen to add more.

You can also copy attachments from other emails. When viewing an email, tap on the action menu beside the attachment files. Select the "Copy" action to copy the selected attachments.
Then you can create a new email and select "Paste Files" from the action menu beside the Attachments list to paste the copied file.