Currently it is not possible to force on certain features on via a query string. In particular this impacts fontsize and pinning functionality.
# QA
Check all the following URLs work for both anons and logged in
https://en.wikipedia.org/wiki/Spain?vectorzebradesign=0
https://en.wikipedia.org/wiki/Spain?vectorzebradesign=1
https://en.wikipedia.org/wiki/Spain?vectortypographysurvey=0
https://en.wikipedia.org/wiki/Spain?vectortypographysurvey=1
https://en.wikipedia.org/wiki/Spain?vectorclientpreferences=0
https://en.wikipedia.org/wiki/Spain?vectorclientpreferences=1
https://en.wikipedia.org/wiki/Spain?vectorlanguageinheader=0
https://en.wikipedia.org/wiki/Spain?vectorlanguageinheader=1
https://en.wikipedia.org/wiki/Spain?vectormainmenupinned=0
https://en.wikipedia.org/wiki/Spain?vectormainmenupinned=1
https://en.wikipedia.org/wiki/Spain?vectorpagetoolspinned=0
https://en.wikipedia.org/wiki/Spain?vectorpagetoolspinned=1
https://en.wikipedia.org/wiki/Spain?vectorstickyheader=0
https://en.wikipedia.org/wiki/Spain?vectorstickyheader=1
https://en.wikipedia.org/wiki/Spain?vectorlimitedwidth=0
https://en.wikipedia.org/wiki/Spain?vectorlimitedwidth=1
https://en.wikipedia.org/wiki/Spain?vectortocpinned=0
https://en.wikipedia.org/wiki/Spain?vectortocpinned=1
https://en.wikipedia.org/wiki/Spain?vectorcustomfontsize=0
https://en.wikipedia.org/wiki/Spain?vectorcustomfontsize=1
https://en.wikipedia.org/wiki/Spain?vectorcustomfontsize=2
https://en.wikipedia.org/wiki/Spain?vectorcustomfontsize=3