The "Weird" route, otherwise known as the "Snowgrave" route, shows the darker side to Deltarune in a very similar fashion to Undertale's genocide route. There are lots of small dialogue changes where the player can be slightly crueler to the rest of their adventuring party and other characters, though these don't have much of a wider impact on the story. Despite this, it would be out of character for the creator of Undertale to completely free you from the consequences of your actions if you made some morally questionable decisions.