rhino has the concept of world coordinates - the once that are written to the file.
and there are cplane (construction - plane) coordinates.
you can have as many cplanes as you want and save them in the “_namedCplanes” panel.
(and then restore them)
of course you can always access / restore the default, world plane.
as soon as you have a custom cplane you can look on it in parallel projection using the command
_plan
(sorry a house is easier then a car…)
to explain it
a house in world / global coordinates
a custom cplane on the roof to construct the solar panels
the command _plan will then look onto the roof
(A) to fully reset right-click on the blue viewport name “perspective” → set view → perspective
or
(B) use ctrl + shift + RMB to free the view from the plan … (the view is still parallel projection then)
check the following commands in the help
_cplane
_plan
_namedCplanes
_namedViews
hope this helps - kind regards -tom