Nylon and Spandex or Polyester does not shrink in the dryer under normal conditions.
To shrink nylon, spandex or polyester you have to use boiling water or other high heat to shrink it.
You can shrink polyester and spandex.
The key to shrinking polyester and spandex is to use heat and the best way to shrink polyester or spandex is to get some water boiling in a pot and then after the water is boiling dip the polyester or spandex into the boiling water for a few minutes.
The heat of the boiling water should shrink down the polyester or spandex but be careful to not leave the polyester or spandex in the boiling water to long as it can melt.
Melted Polyester is toxic to breathe in.
When polyester melts it can produce toxic fumes that can cause lung issues so if you have melted polyester and there's a smell you should open windows and get some fresh air in.
Polyester is a plastic and when plastic melts it produces toxic chemicals that can lead to lung cancer and other lung issues.
You can tumble dry polyester in the dryer but you should use the cool setting and not the high heat setting as it could melt the polyester.
Polyester Garments can go in the dryer.
When drying polyester in the dryer set the dryer to the cool setting so that the polyester does not shrink or melt.
Polyester is not regular fabric and not cotton so you need to dry the polyester in the dryer on the cool setting or it could also melt.
Polyester is a man made fabric that is made of a plastic and when being dried in the heat setting of the dryer the polyester could melt.
Shrinking polyester is hard to do under normal circumstances but sometimes the polyester may shrink in the dryer especially if you use the heat setting.
Or you could just hang the Polyester out to dry outside on a clothesline or in the house.
But using the cool setting on your clothes dryer you can safely dry your polyester.