My experience: A few metres, depending on the size of the object. Ring facts sheet: up to 250 ft, that would be approx. 50 metres. I can't judge, all my monitored corridors and rooms are (unfortunately) less than 50 metres :-)). Interesting: Ring claims that if the sensor is mounted at the right height, it will not be triggered by pets. I can neither deny nor confirm this. In general, I would be cautious that a cat in the house, for example, could trigger the alarm after all.

Our dining room measures around 10 metres diagonally and it can cover this distance well.
In general, I'm impressed by the quality of the ring hardware: it can easily keep up with professional infrastructure (we previously had Siemens/Vanderbilt) and the configurability is unrivalled.
If in doubt, simply install several motion detectors :)

Mine still reacts at 8 metres, but only if I'm not partially covered by furniture. I can't say whether it is sufficient for more.