It is normal for 6 year old boys to wear diapers all the time in some cases as some 6 year old boys have disabilities that prevent toilet training and some 6 year old boys may be urinary incontinent.
It's also normal for some 6 year old boys to wear diapers all the time even just out of comfort and because they enjoy diapers.
It is not weird at all for 6 year old boys to wear diapers.
While the majority of 6 year old boys are potty trained and no longer need to wear diapers at least during the day, it's perfectly fine and normal for 6 year old boys to wear diapers when they need to wear them.
Some 6 year olds are urinary and or bowel incontinent and need to wear diapers all the time and some 6 year olds may have autism or other disabilities that prevent toilet training and require the 6 year old boy to remain in diapers.
And it's also common for 6 year old boys to wear diapers or even pull ups like Goodnites for example for bed wetting.
There's no age limit for diapers and if the child needs to wear diapers, then the child should wear the diapers or pull ups.