Beds with storage under matress can have hydraulic parts (sorry, don't know how they're called exactly) to help lift the matress. Example:

https://www.ikea.com/pl/pl/catalog/products/80404078/

Yes, this is the exact model. https://www.pepperfry.com/taro-queen-bed-with-hydraulic-stor...

this just came to my mind https://i.gifer.com/B514.gif xD

Ottoman

Waterbed?