Implementing confidential mode is a fairly easy process that's similar across both Android and iOS.
Android and iOS users are now able to use the new Gmail Confidential Mode. Confidential emails will automatically have the ability to forward, copy, print, and download removed, so the recipient won't be able to make copies of your original email. Also, the confidential mode feature isn't now available for G Suite customers. Now when you send the mail to a particular recipient, they will have a specific time limit to check the mail after which it will be expired. Tap on that and you'll be given options to set a passcode for the email, an expiration date, and more. Users using Gmail with a work or school account will need to contact their administrator in order to use confidential mode. Many new features were added that built on work Google had done with other applications and were finally bringing over to the email platform. Along with the control options, users can decide whether they will require recipients to obtain an SMS passcode before they can access the email message. Confidential mode is rolling out to mobile devices today, so be sure to keep an eye out for it.