This looks more likely habitual
Needs proper encouragement
Best way is give him time in the morning
Some time to pass the stools
First you give him 1/2 cup of warm water
Coffee is good bowel pusher 😁
Ask to out side say in varanda to clear it
As some children do not like bathroom smell
Next Steps
add cereals and greens and vegies carrots salad to lunch
add gigily oil to food
avoid biscuits for sometime
Health Tips
you can do 1 tyroid test 2 U S G abdomen
show the result to your family doctor
to rule out any pathology
thank you