It depends, normally you do not want to reinvent the wheel. Therefore you should use a pre-made design system most of the time. However, if there are specific requirements you need to accomplish, that may require you to build one on your own.
@y_gao I was more interested in finding out if a kit like that for Webflow/Figma exists would people use it, so the build would look 1:1 with the design.
And then, the time to be saved could be quite a bit.