Can I manage another new account in QuickBooks with existing subscription plan ?

what do you mean with "manage"? If you have another company/branch with different tax ID, you should open a new QBO account. You may use the same email address to open it.

https://quickbooks.grsm.io/India

But if you are an accounting/bookkeeping firm, you may open a QBOA account to manage your client accounts in a single dashboard.

Hope it helps.