Configuring preferences and options in Outlook.com
Go into your "Developer Options". Scroll until you find one that says something to the effect of: Force apps to use SD card (or external).
Depending how you access files on your device & the brand, when you are looking at the storage map of your device (or when you access Outlook via APPS in Device Settings, there will me an option to install on your SD card.
The wording changes and with the last Android update for my Samsung Galaxy (yesterday) some system & app operations have moved under different headings.
If my solution is a bit convoluted, do a Google search for "Force Apps to use external Android.
✌👍
Yes but: "You won't be able to add a micro-SD card to the Pixel," which is what I have. In any case, using an SD card is only a workaround. Microsoft should fix the Outlook bug.