@Kriszta - basic syntax to sort:
Sort(
'Your List',
Final_Deadline,
SortOrder.Ascending
)
By "pre-define", I think you mean Filter:
Sort(
Filter(
'Your List',
Final_Deadline>= DateAdd(
Today(),
-14,
TimeUnit.Days
) && Final_Deadline <= DateAdd(
Today(),
14,
TimeUnit.Days
)
),
Final_Deadline,
SortOrder.Ascending
)