You can mix up an enamel wash,I usually use burnt umber,mix it with thinner,90-10 %use an acrylic gloss over coat,this will allow your mix to flow down the panel lines and in to crevices.Then you cover it with a flat coat.
An enamel,oil,or lacquer wash will not harm a well cured acrylic coat,but don't use it on enamel basecoat.
A company called Flory makesva nice panel wash,as do Mig,AK,and Vallejo,but you can mix your own.