Hello! I just wanted to ask what age should a child be sleeping on a stretcher bed? As there’s a child at my centre who has special needs and is 2 and a half who still sleeps in a cot. Thank you!

There is no specific age where a child must be placed for sleep on a bed/stretcher.
The guidelines for moving from a cot to a bed are related to safety.
Red Nose has the following information.

For safety reasons, when a young child is observed attempting to climb out of the cot and looking like they might succeed, it is time to move them out of the cot.
This usually occurs when the child is between 2 and 3.5 years of age but could be as early as 18months.
https://rednose.org.au/resources/education