The dip now works backwards. 1 or 2 Paladin/X Warlock.
Two levels in Paladin grant you heavy armor, Smite and additional spell slots to burn for things like Smite, Shield and whatnot. The rest in Hexblade for the higher level slots and invocations.
Because of how rushed the development of OneDnD was, there are tons of inconsistencies in how features work, and one of them is Divine Smite requiring a bonus action, and Eldritch Smite being part of the attack. Because of this (and the removal of the level cap on Divine Smite), the best smiter is a Hexblade with two levels in Paladin who can cast both Smites on the same attack and using higher level slots than the class that should use them.
Depending on how they rework the subclass (we've got two UAs that are very different from one another and from the previous incarnation of the subclass in the 2014 rules), it's got a chance at becoming the best gish build.