Spexi provides WMTS and XYZ tile service URLs that you can add directly into ArcGIS Online as a web layer.
Important:
XYZ service URLs cannot be added as a permanent “Item” in your Content, however, ArcGIS Online does support adding external XYZ tile services directly into a web map.
ArcGIS Online allows you to add WMTS layers as a new item by supplying the URL and adding a custom parameter for your API key.
Add Spexi Orthomosaics as a WMTS Layer
Use this method if you are working with the WMTS URL provided in the Spexi Integrations page.