No. The SQL CREATE PROCEDURE
statement doesn't allow 'like(somecolumn)'. But that's a good thing, because that interface is a contract between the stored procedure and all of its callers. If that interface could change dynamically, how would the callers know how to allocate memory for the variables? Ultimately, if the underlying column size changes, you need to find the stored procedures using that column and all of the callers of that stored procedure and change them all together. Imagine for a moment that one of those callers puts the column up on a 5250 display, or prints it on a report - you need to make room for the newly enlarged column.
One way to make that burden lighter is to create a new stored procedure (GetCustomerAmountDue_v2) which uses the new, longer column definition. Then any caller which needs that longer definition can be changed to call the _v2 procedure.
If your column is a character column, then it's possible for you to return a VARCHAR instead of a CHAR; the interface doesn't need to change because the contract already allows for a varying number of characters to be returned.