On menus, perspective is everything. Place incredibly expensive item near the top of the menu (non prime location), which makes everything else seem reasonably priced.
Place this near your high profit margin items. They may already have a reasonable price, but when compared to the “decoy” item, they will appear even more attractive. Or, put a “decoy” item next to your high-profit, pricey items that would seem more reasonable when compared to the “decoy” item(s).
Include two portion options for one dish without including the exact size. The “larger” size will have a steeper price, such as 28, while the “smaller” size will have a seemingly cheaper price, like 18.