See if you have a 2 year gap after 12th then you don't need any such gap certificate. If you wish to give entrances like JEE Advanced then you can't as it has a limit of 2 years attempt where the first attempt is the year of boards. But for most entrances there are no such restrictions. Also if you wish to take admission to course which gives admission without entrance then also they will consider your 10+2 results. So overall you will not need any such certificates. But if your college wants it (which is extremely unusual) then you can obviously ask the proforma prescribed the college.

I hope this answer helps. All the very best for your future endeavors!