S.H.
Even if a 5 year old child is pulling their own wheelie-suit case... they do not walk as fast as adults. And in a "crowd" as there often is at an airport, they are not as fast as the adult.
Hence, you will probably have to help him.
And it depends on how heavy, his bag will be.
Heavy bags, wheels or not, are hard for little kids to carry or pull.
And it also depends on how long the distance is that they have to walk, at the same time, while pulling or carrying their bag. Or if going up or down stairs, etc.
My kids have wheelie school bags.
It gets full of stuff. It gets heavy.
Sometimes my 5 year old needs help.