It is not normal for your 6 year old boy to not be potty trained and wear diapers.
Unless the 6 year old has developmental issues or Autism that prevents him from potty training then the 6 year old should be potty trained by now and no longer need to wear diapers.
However it is normal for the 6 year old boy to need to wear diapers at night when they sleep for bed wetting.
But during the day the 6 year old boy should be able to use the toilet normally and no longer need diapers.
But if the 6 year old boy requires diapers due to any issues including incontinence then it's okay for him to wear diapers.
Most kids are potty trained by age 2 to 3 years old although some kids may take as long as 4 to near 5 to potty train.
If your child is not potty training by 6 then you should really force the issue and if needed discuss the issue with the 6 year olds pediatrician.