Be careful... Epoxy is a blessing and a curse.
Total encapsulation, or no encapsulation and not much in between.
Don't put epoxy over it, if it is solid stock, or if the lamination layers are much thicker than a 1/2 inch a piece. On large timber, or thick laminate about all you can/should do is epoxy coat the end grain, and pot in any bolt holes or mounting points.
The wood will either be mostly dry, or mostly wet when you put it on and the next season is apt to break the epoxy, LPU, varnish, polyurethane
and let moisture in but not back out. All the bolt holes need to be overbored and filled with thickened epoxy. Mounting holes and every inch of surface need to be coated and sealed.
If the wood moves, and cracks the existing varnish every season it isn't a very good candidate for epoxy encapsulation unless you can get it dry and believe you can keep it dry. Otherwise, the next season it'll crack the epoxy and then wooding it back down will be a patience trying experience. Wet, epoxy encapsulated wood is not wood that lasts very long. It cannot breath, and cannot dry out.