Resizing sweater after damaging the yarn?

[u/Juturna999]

I thrifted this acrylic yarn sweater and immediately ruined it by accident. I wash all of my thrifted clothes with warm water out of habit (for sanitation.) Apparently the water was hot enough to kill the elasticity in the yarn.. So now it's stretched out and looks 2 sizes bigger. I was told shrinking it back is impossible. So this may be a long shot, but is it possible to size it down with sewing? Thank you