Most children who are healthy and are eating a healthy diet and eating enough fiber should poop at least once everyday.
However all children are different and it's okay if the child goes 1 or even 3 to 4 days without pooping if they are not eating enough fiber.
Not every child or every adult needs to poop everyday unless they eat a lot of fiber.
So if your child does not poop everyday then there's likely nothing wrong with them unless they were pooping everyday and then suddenly the child has stopped pooping everyday.
Then in that case the child may be constipated.
But as long as the child is pooping a few times per week or so they should be okay.
There's sometimes my kids went 5 to 6 days without pooping and then suddenly they would need to poop.
I'm not sure if they were just holding in the poop or they just didn't need to poop but they were fine and still are fine.