To attach a photo or video to an email you have already started in Mail on a current iPhone, tap in the message where you want to insert it, then tap the Insert Attachment Actions button above the keyboard. Choose Photo Library, select a photo or video, and tap Done. To capture something new, choose Take Photo or Video instead. If the file exceeds your email account's attachment size limit, follow the onscreen instructions to send it with Mail Drop.
Attach a photo or video in iOS Mail