or don't, whatever, but this ⬆️ is why
Left: unblocked
Right: blocked
edited to add: you definitely don't always need to stretch to shape/size—mostly what I'm trying to show off here is how much smoother and more elegant the stitches look after blocking!
here's a tutorial on how to block: https://brooklyntweed.com/pages/blocking-101
side note: some things don't need aggressively blocked, but even then, doing the washing and drying will benefit your knits! follow the initial description, and then just gently pat your knits into shape and let them dry on a towel. this will let the stitches even out, and lay flat and neat!