There is an official parts data base here which are the parts in core parts. That only contains parts from here (or the wider net) if someone makes a pull request on github. That hasn’t been happening a lot in the last few years though (I am as guilty as anyone, github and I typically don’t get along )
First be lazy (I always am ) a google search of the form “fritzing part part-name” (i.e. fritzing part SD card module) will find any existing parts on the net so you don’t reinvent the wheel. That said, “parts submit” here in the forums is my usual place. In the past things posted there got moved in to core parts but that hasn’t been the case for a number of years now. If you are considering making your own parts (which is quite complex and poorly documented in general) these two tutorials may help. Both apply to the current versions of Fritzing (many of the others are for older versions)
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