At what age can a child color inside the lines

Those coloring workbooks and giant coloring books at what age can a child successfully color them.

Without scribbling?

To me art doesn't have to be about coloring inside the lines I see the beauty in things like finger paintings and watercolor, oils etc.

But I understand in kindergarten as a child they wanted me to color within the lines it was a must and most activities consisted of that besides naming the colors. Is this something important to learn at what age?

What are things children can learn to prep them for kindergarten first grade?

What is the most fundamental thing you want to teach your children and how will you teach them?

Parenting advice is welcome