See there are no such maximum age for Private sector although, its highly advised that to start the career in private sector its better to do under 35 because with higher age and lower experience, the companies don't find any interest to recruit them. Now if you have work experience and you are at a higher age then the companies do recruit but without experience it can be a less probable, although I would obviously suggest you to try.

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