Is this suitable for a 5 year old?
No, not really. The stroller had quite a few bad reviews about its lower quality, so it may be such a strain - higher eight, larger child - may make the push truly uncomfortable and the frame get damaged. In theory, you can kind of fit a 5yo in, but I personally would not go for such a use with this lower-quality, cheaper stroller.
Your -very berry- Eli.