Search Bar default value based on relation to current user

Hi,

I would like to have an option to add a default value in a search bar in the data grid / template grid, that will be filled with a value that the Account is linked to.

F.e. when an Account is linked to a region, and on a datagrid, all users are being shown, and there is a search bar on region, I want to have the default value the region of the current user.