Originally Posted by
ZeroBG82
Given the way Elden Ring works, you absolutely should be able to. They will introduce some means of accessing the new area (looks like through Miquella's cocoon in Mogwhyn Palace) and all you have to do is go there.
In past games you were forced into NG+ right after completion, which meant completing the game up to wherever you can access the DLC fresh unless you had a save prior to that point, but in Elden Ring you just load back into the world after the ending. So any completed character should be able to access the DLC area straight away unless they change things up for some reason. It sure looks like the only condition will be defeating Mogh to access the cocoon.