Final Boss (Elden Ring)

First you should go through the map to the Fire Giant. Kill him. Go further to the Giant's Forge and talk to the girl at the save point. Spoilers ahead, but you'll get to the right place. There is a bug, after passing you will be given a choice - Start a new game + or not. So, if you don’t start, you stay in this game world, but don’t teleport to the ashen city, otherwise you may not get out later, because the bosses will be killed, and the points of grace will be closed.