I don’t think you can with the default Mendix options. You can combine the expression with the ‘ show...for selected users’ checkbox bellow it, but then you get an ‘and’ expression.
You could just create a copy of the grid and always show this for the admin and then for this grid, do not show it to the admin.
Or use a widget like this: https://marketplace.mendix.com/link/component/2539 where you can set the visibility with a microflow or nanoflow