I would like a larger set of symbols for ArcGIS symbology. Are there ad-ins available for downloading and using in ArcGIS Pro?
There is guidance here about adding styles to an ArcGIS Pro project: Add styles to a project—ArcGIS Pro | Documentation
(You might not be but) if you were previously an ArcMap user, there is a section in there that is specific to importing ArcMap styles.
A quick tip for the future - when asking something specific about ArcGIS Pro, there are a lot of very helpful users with eyes on the ArcGIS Pro space, so posting there could help get a response.
I hope this helps!
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