Current ESRI product allow you search multiple layers, even from multiple sources.
Here is a example, you have to click drop down arrow to select which layer you want to search.
Omni search is different, you do not have to choose which layer to search, it automatically search every layer, everything, every resource in your organization.
Most of time user don't know what layer to search against. Omni search is more intuitive, more easy to use compare to the curent ESRI's provided search widget.
https://www.fire.ca.gov/incidents/2024/9/5/line-fire
current ESRI product provide you this search widget, user have to know what layer they want to search for,
The hard part is user don't know which layer to search for.
User want to search for all layers without knowing which layer to pick.
That is what omni search will do
https://sbcounty.maps.arcgis.com/apps/webappviewer/index.html?id=35f8f75a490f4007bc983b39c208a629
