I found these lines below online.

I've always been a color-inside-the-line kind of guy, especially when the boundaries are black and white.

Could 'a color-insidej-the-line guy' mean a perfectionist or something?

In school, children are required to follow lines, cut on the line, color inside the line and write between lines.

To color inside the line means to be on your good behavior, right?

Right. I don't think "perfectionist" applies so much as "following the rules," "not making waves," "not pushing the envelope," "do what's expected," "don't stand out."

"Be on your good behavior" is fine. (A perfectionist would stand out.)

- A.
Thank you, Avangi.

Got it!