@SmartyAadi and @ogghi it does exist. It just isn’t the format you might be thinking. You add new search engines under Site Search. Then you can Make Default and it will become your default search engine and will shift from Site search to Search Engine.
I did !n just because. You can type in any shortcut you want. When you don’t have it set to your default search engine, it stays below on Site search, such as you see below: