Hi, RRK_ME
Welcome to the MicroSoft Community.
I was wondering if your sidebar button is disabled? Are you a personal account or a business account? If you are a business account, the function may have been disabled due to organizational policies. The phenomenon you described seems a little strange. I know that the sidebar can indeed be displayed or hidden through the switch setting, but I haven't found any switch that can turn off the search bar. Could you please provide the corresponding screen shots or videos? In addition, please provide the following version of your MacOS and the version of your current Edge so that I can better understand your question.
Best Regards,
Martin | Microsoft Community Support Specialist