Questions about web selections from a host as it relates to Internet devices.

I have a question about Adobe XD and then turning a desktop website, a tablet size website and a phones sized website into functioning websites.  Once completed in XD and turned t into functioning websites with code manufactured by WordPress by Yoda can the size alter?  If the monitor size, tablet size, or phone size of another device is larger or smaller than art board sizes, do these websites alter to fit other screens?  Do they adjust themselves to different monitor sizes etc. phone sizes etc.?  

How do Internet devices distinguish between monitor, tabloid, and phone sizes from a host?  How does a cell phone select the cell phone version as opposed to a monitor or tabloid? I suppose it does and it should not be a concern.

When you have built portfolio web sites, will Adobe cloud have a hosting function for the members of Adobe? 

I would appreciate any input to these questions as I am new to XD.

Thanks Bill