The model is regenerated.

VIEWRES controls the appearance of circles, arcs, splines, and arced polylines using
short vectors. The greater the number of vectors, the smoother the appearance of the
circle or arc. For example, if you create a very small circle and then zoom in, it
might appear to be a polygon. Using VIEWRES to increase the zoom percentage and regenerate
the drawing updates and smooths the circle’s appearance.

When a named (paper space) layout is made current for the first time and a default
viewport is created in the layout, the viewing resolution for this initial viewport
is the same as the viewing resolution for the Model layout viewport.

The VIEWRES setting is saved in the drawing. To change the default for new drawings,
consider specifying the VIEWRES setting in the template files on which you base your
new drawings.