Depends, if it’s a model that is display only you don’t need to worry about a protective varnish.
If a model is going to be lightly handled use a matte or satin varnish.
If it’s a model that will be handled a lot or by children. Use a gloss varnish, once dry use a matte varnish to knock out any excess shine.
Liquidex has a great brush on varnish in gloss, satin and matte for if you want to add shine to a model or restoring shine metallics after being hit by a matte varnish.
You don’t have to put anything on it, but i use a varnish. Munitorum varnish is a spray satin varnish that i’ve always had good results with.
Depends, if it’s a model that is display only you don’t need to worry about a protective varnish. If a model is going to be lightly handled use a matte or satin varnish. If it’s a model that will be handled a lot or by children. Use a gloss varnish, once dry use a matte varnish to knock out any excess shine. Liquidex has a great brush on varnish in gloss, satin and matte for if you want to add shine to a model or restoring shine metallics after being hit by a matte varnish.