When you try to find the Delay Delivery button in Outlook 2016, you’ll find by default it’s missing (it’s hidden!). To delay delivery of an email in Outlook 2016, you have to click the Pop-Out button so the email is in it’s own window. When the email isn’t in it’s own window (say, if you hit reply or forward, instead of creating a new one), the Options tab containing the Delay Delivery option is unavailable.
On the email window, click Options, then Delay Delivery. you can then fill in the settings to delay the delivery of the email.