Using classic Outlook for Windows in educational settings
Quick parts is still in Outlook. But it is hidden in a menu option not obvious it needs to be selected. I added Quick Parts to my QATB, "but" it won't render until I open a new email template. IMHO it doesn't help that both the Ribbon and Quick Action Toolbar change depending on what Outlook template you are working in.
Example here is my | In Box | QATB without Quick parts rendering:
Start an email. From the newly rendered menu bar select [Insert] and look in the | Text | section of the ribbon.
And now the Quick Parts I've added to my QATB is rendering.
It's literally mind boggling to me why anyone would think a product used primarily for business communications should have illustrations more prominent than items used to increase productivity. IMHO the marketing people need some adult leadership.
Ron
The OP is referring to the new Outlook App from the MS Store. QuickParts is not available in that version at this time (hopefully MS will put that feature back soon).
Apps > My Templates.
Template.