I had an issue come up today where a user wanted to search a SharePoint list by the default ID column.
Problem:
The ID column cannot be indexed and is not searchable using just the ID number itself.
Solution:
You can still search ID numbers in lists if you include the proper Keyword Query Language (KQL) syntax. Format your search as ListItemID:3 (replacing 3 with your own ID number, of course) and it will work.
And yes, this works in both modern and classic list search experiences and in SharePoint Server and SharePoint Online/O365.
It doesn’t appear to work on Teams sites
Why do MS make you go through that particular hope I wonder? It only has a purpose in excluding other fields to allow focus, but in a general sense it would be more user friendly to include the ID field in a ‘list wide’ search of all searchable columns. Still, good work on finding an answer to the question, Nate 😉