In BG series paladin must and only start from LG, however, there also another type of paladin---- fallen paladins.
Fallen paladins are LE , they have same or maybe more powerful fighting ability than before. But they lost connections with their Order. These maybe a bit different to book rules in 5th or 4th when playing physical dnd games.
Indeed, BG3 uses a variation on D&D 5e so paladins are handed quite differently than in BG1/2. It's still possible to play a typical Lawful Good paladin (which from what I can tell probably maps best onto the "Oath of Devotion" paladin in 5e), and there's also a type of "fallen" paladin subclass called an "Oathbreaker" (I don't recall this as a class in BG1/2, though I think it was the Extended Edition that introduced the "Blackguard" subclass which I guess could map to either Oathbreaker or Oath of Vengeance depending on how you wanted to play it). In BG3 we can't start as an Oathreaker, though we can as a Vengeance paladin, but we can become one pretty quickly. In the initial release we'll also have Oath of Ancients paladins, who would be good but not necessarily lawful.
