No, no, like building the setting from scratch, while drawing on whatever referents for “fantasy” that you want, and then building a system from scratch to match that setting.

So if you wanted something like Exalted, you might take

In:
Epic heroism
Martial arts
Godly powers
Magic-tech
Elemental magic
Land spirits

Out:
Zero-to-hero
Good vs. evil

As your answer to this question, and then if the system needs to be build around that list of parameters, then so be it.