Many years ago we used to feed our dogs a high quality kibble made in France. I think the name was Flatazor or something like that. It was a large breed formula with about 26% protein.  The dogs grew normally for big dogs. From fluffy round bodied puppies at 2 months to tall lanky ungainly things at 6 months.  Started taking on muscular strength and forming at 8 months and grew to 90% height by 18 months and full height by 24 months.  They began filling out structurally at about 14 months and continue until about 36 months.

So the keep it simple - by 18 months they were almost finished growing in height with just another 10% to go.  They are completely in form and height by 24 moths and continue to mature structurally until about 36 months.

I suspect that kind of growth rate is common among the molossers, mastiffs and bullies.

In 2003 we switched from kibble to a completely raw diet for our dogs.  Have not had any health issues since them.