I think it is unlikely but is there any workaround or customization possibility to sort the result other than “Created time” or “Relevance” when searching in apps?
Or “Created time” can be overwritten manually?
We would like to sort the result by the Date field in the app rather than the system field “Created time”. We know custom fields in the app cannot be used to sort the search result.

Hi Mo,
Unfortunately, the whole search criteria cannot be customized and there is no workaround in your case.
Well we might be able to do it in the whole customization, but because the API to the full-text search is not available, there is no way to change the sort condition. There might be a way of making it from the scratch, but I think that it is not realistic.
You might already know but if I want to sort the record based on a specific field after the search result on a specific field, I would create a new view that has a filter and sort condition setting, which might be different from what exactly you are trying to do this time thought. With this setting, you would need to know the field that includes a search word. Please see the link below to learn how to set up a sorting and filtering on a view.
▼ Creating Views > Filtering and Sorting Records
https://jp.cybozu.help/en/k/user/whatsview
Thanks.
Junko