Getting value from a property according to some parameters
Probably the direction is correct but the class API is inconsistent for now. DateFrom is available, DateTo is not.
As for me, the following way looks more consistent.
public class MainApplication : Application
{
    public DateTime DateFrom { get; set; } = DateTime.Now;
    public DateTime DateTo { get; set; } = DateTime.Now;

    public DateTime GetSearchDate(bool isDailySearchEnabled)
        =&gt; isDailySearchEnabled || !PurchaseFunctions.HasPurchasedDateRangeSelection() ? DateFrom : DateTo;
}