Do I need a top coat over Deep Pour Epoxy on a table or bar?

Yes. Use UltraClear Deep Pour Epoxy only for the deep part of the project: the river, voids, embedded objects, anything 1/4 inch or thicker. It is not meant to be a stand-alone finish on a table, bar, countertop or any surface that sees regular use. It is softer than UltraClear Bar & Table Top Epoxy, and since it cannot be poured thinner than 1/4 inch it can't be the final flood coat either.

Finish the surface with Bar & Table Top Epoxy. It self-levels to 1/8 inch, restores the glass-like finish, and gives you a durable, scratch-resistant wear surface. It is also what seals the wood before the deep pour. On a river table or bar that means a Bar & Table Top seal coat, Deep Pour for the river, then a Bar & Table Top flood coat over the whole top. After the last Deep Pour layer, let it cure 3 days, scuff-sand with 220-320 grit, clean with denatured alcohol or acetone, seal coat any exposed wood, and pour the flood coat. Step-by-step guide: https://ultraclear.helpscoutdocs.com/article/859-table-top-epoxy-deep-pour-epoxy-river-table

The top coat is a recommendation for surfaces that get used, not a rule: for a decorative casting or a piece that won't see wear, Deep Pour can stand alone, and plenty of customers use it that way. For a non-epoxy finish, Osmo Polyx-Oil is an option (it comes in matte); test first.