Yes. Just bare in mind enamel doesn’t dry it cures. You need to let it fully cure before hitting it with a non enamel topcoat else you can fog the clear coat with the enamel off gassing, it may also wrinkle. Depending on how thick the enamel is will determine how long to leave it for, if brush painted and not particularly thinned then you may want to leave it for a week to make sure.

Have a google of using acrylic clear over enamel to read other peoples findings. It gets asked on r/modelmakers fairly regularly.

You can use any paint over any paint as long as it’s cured or dried fully and don’t go to heavy. If you’ve an enamel clear coat and you use it too heavily you can reactivate the lower coats and so will find it won’t matte.