They commonly use elastic waistbands, and some versions add an adjustable drawstring combined with the elastic for a customizable fit.
You can find at-thigh shorts and full-length pajama bottoms in this pizza-themed category.
Care instructions typically call for machine washing and tumble drying. Some listings specify machine wash cold with like colors and tumble dry on low.
Listings generally describe a classic (regular) rise with a straight-leg, regular fit for these pajama bottoms.
They use a pull-on closure, typically combined with an elastic waistband for ease and comfort.