With D365 CE there are lot of cool stuff's happening, we are right in middle of all the rapid evolution of the industry and product.
Its always handy to have URL's in armory to navigate to specific areas/interfaces with ease. Lets have a look at them now
Before reading below content around UCI/Classic app, its recomended to go through below blog,
How to quickly navigate to default Class UI app when the "UCI only" setting is enabled?
Append a forceclassic Query string parameter after main.aspx
https://<your orgname>/main.aspx?forceclassic=1
Ex: https://contoso.crm.dynamics.com/main.aspx?forceclassic=1
How to quickly switch the current UCI app to Classic UI?
Append a forceclassic query string parameter after appid. Please make sure to remove session idenfier("#<somerandomnumber>") before appending foreclassic tag.
https://<your orgname>/main.aspx?appid=<yourappid>&forceclassic=1
Ex: https://contoso.crm.dynamics.com/main.aspx?appid=ec876248-c755-e911-a832-000d3a127836&forceclassic=1
Happy Learning!