I have not found rules for creating new special maneuvers in Street Fighter RPG. Is there an official book that has rules for this?
The system does not give any rules on how to create new moves. Instead, the list of moves that exist to be selected from is intended to be exhaustive and balanced, and any attempt at creating a "new" move is done by re-skinning an existing move with your own name and flavor while remaining mechanically the same. The book justifies this with examples, such as explaining that Guile's Sonic Boom and Dee Jay's Air Slasher are essentially the same move.
The 20th Anniversary Edition is a fan-community-made compilation and rebalance-mod of all the moves and mechanics from all of the supplemental books, as well as fan creations from the newer entries in the video game series (such as characters from Street Fighters 3, 4, and 5), and should have a higher quantity and quality of moves to select from compared to the original version.