Desc Emp;
Empno NUMBER(5)
Empname VARCHAR2(10)

Create procedure P1 (p_name emp.empname%TYPE) IS
begin
 Dbms_output.put_line ('Name :'||p_name);
Exception 
   When others then
          Raise_application_error (-20999,'Error in P1 :'||sqlerrm);

End;

EXEC P1('1234567891011231345');
Result=> Name :1234567891011231345

SQL> Create or replace procedure P1 (p_name emp.ename%TYPE) IS
  2    subtype mytype is varchar2(10);
  3    l_name mytype := p_name;
  4  begin
  5   Dbms_output.put_line ('Name :'||p_name);
  6  end;
  7  /

Procedure created.

SQL> exec p1('1234567890')
Name :1234567890

PL/SQL procedure successfully completed.

SQL> exec p1('1234567890X')
BEGIN p1('1234567890X'); END;

*
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
ORA-06512: at "MICHEL.P1", line 3
ORA-06512: at line 1

SQL> Create or replace procedure P1 (p_name emp.ename%TYPE) IS
  2    subtype mytype is varchar2(10);
  3    l_name mytype;
  4  begin
  5   l_name := p_name;
  6   Dbms_output.put_line ('Name :'||p_name);
  7  exception
  8    when VALUE_ERROR then
  9      Raise_application_error (-20999,'Maximum name length 10 (actual: '||length(p_name)||')');
 10  end;
 11  /

Procedure created.

SQL> exec p1('1234567890X')
BEGIN p1('1234567890X'); END;

*
ERROR at line 1:
ORA-20999: Maximum name length 10 (actual: 11)
ORA-06512: at "MICHEL.P1", line 9
ORA-06512: at line 1

SQL> create or replace type mytype is object (ename varchar2(10))
  2  /

Type created.

SQL> Create or replace procedure P1 (p_name mytype) IS
  2  begin
  3   Dbms_output.put_line ('Name :'||p_name.ename);
  4  end;
  5  /

Procedure created.

SQL> exec p1(mytype('1234567890'))
Name :1234567890

PL/SQL procedure successfully completed.

SQL> exec p1(mytype('1234567890X'))
BEGIN p1(mytype('1234567890X')); END;

*
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
ORA-06512: at line 1