Drafting Views can be loadable so you could utilise these and does exactly what you are asking but as I recall you cannot save a legend view using the Save to Library > Save Views in the File menu,
A common workarounds is to copy and paste the components or symbols from the legend view into another projects legend view. You can place a bunch of legend views on a Sheet, select all of them and copy paste from one project to another. You can select a legend on a Sheet in Project A, CTRL+C, and paste on a Sheet in Project B.
Most users would typically create or place legend views into the Project template file if they are repetitive.
The final method is to use and add-in such as pyrevit as this has a dedicated tool for Transferring Legends.
Jay Colcombe
Autodesk Certified Instructor
Revit Architecture & Structure Certified Professional
AutoCAD Certified Professional
B.Sc. Hons Civil & Structural Engineering
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