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
id love to show you this before and after of blocking a crocheted square i did a bit ago. the one with my left hand is unblocked and the one with my right hand is blocked. you can see how it went from all puckered and wavy to a much flatter fabric, and i can tell you its drapier than it was before as well