You will be able to play as a plethora of new; races, subraces, classes, and subclasses as well as have access to additional character options like extra warlock pacts and possibly extra spells. However this is your story, make the hero you want to. You can obviously ignore these and choose the standard player options if you prefer, just be aware that most of these things were made by experienced designers [Except my homebrew race the Titianborn based heavily off the mechanics of the duergar] and I think there pretty balanced and flavorful options, either way,