Yes, Rayon can shrink. The core cause of rayon shrinking is exposure to certain conditions, especially heat. Overheating can occur during the washing or dry....
https://www.aanyalinen.com/blogs/aanya-blog/does-rayon-shrink

Twin Flat Sheet Size in inches 66 Inches x 96 Inches. Measurements of twin-size bed flat sheets in cm are approximately 168 cm x 244....
https://www.aanyalinen.com/blogs/aanya-blog/twin-bed-sheet-sizes%20

Polyester is heavy and less breathable and is made by man-made substances whereas cotton is breathable and lightweight natural fabric but both are the fabric....
https://www.aanyalinen.com/blogs/aanya-blog/polyester-vs-cotton%20