In case this doesn't seem like a particularly scary situation: https://en.wikipedia.org/wiki/Grain_entrapment#Occurrence

> Half of all entrapment victims eventually become engulfed. A human body in grain takes seconds to sink, minutes to suffocate, and hours to locate and recover.

By raising your legs slowly and lying on your back, you cannot sink into quicksand. I wonder if it is the same for grain.

https://www.wikihow.com/Get-Out-of-Quicksand

There were 29 agricultural confined space fatalities in the US in 2023. Roughly half of the identified cases were caused by grain entrapments.

https://extension.purdue.edu/news/2024/09/grain-entrapment-i...