If you use ISO standard then it’s possible to drag/drop the symbols directly from the ISO library:

E.g.  ISO 7000 / IEC 60417 Graphical symbols for use on equipment

• Click on the Icon you want for the larger view
• Drag-drop the symbol onto the Miro board.

@Brian Herzog - While there is no library/diagram pack for these symbols natively in Miro, to expand on the suggestion by @Shayne Smart , you could upload all of symbols you expect to use to a Miro board, and then add them to your Saved Files library for later use .

Note: the saved files are attached to individual profile and at the team level, so they will only be available to you and on boards in the team to which you added them.