Hello KV Shah.
Yes, you could take your kid. It shouldn't be a problem.
Kids acclimatise faster than adults do :) Just be careful with the little ones clothing. And rest in Leh for 2 days (so that everyone is acclimatised), before heading to higher altitudes like Khardungla or Pangong.
I had an amazing time in Ladakh and would recommend everyone to visit Ladakh once in a lifetime. But, it's quiet unsafe to travel high altitude regions with your children. You can straightaway go by the flights but stay in Leh city for atleast 2 days so that your body can acclimatize according to the environment.