Hi CrystalUQ,
Thank you for reaching out to us. I am Blessing, an independent advisor here and a Microsoft user like you.
I am sorry but it is currently not possible to schedule emails with the Outlook apps for iOS and Android. There is no option for delayed delivery on mobile Outlook App for iOS.
You can submit a feedback to Microsoft using this link https://feedbackportal.microsoft.com/feedback
Hope this helps!