Hello! I want to start buying autumn clothes for my son (he's 2.7 year…

Hello! I want to start buying autumn clothes for my son (he's 2.7 years old, height 93 cm). As you know, I always ordered a size bigger in the past. But now he doesn't grow as fast. He added 2 cm in a few months. And now I don't know if ordering clothes in size 98 will be okay for him, not too big? Especially pants. An 92 size in autumn might be tight already. How do you buy clothes at this age? When they don't grow so fast anymore. My son is thin himself.