Can I make an IMPS/NEFT/RTGS transfer from an unlinked bank account or someone else's account? (third party transfer)

As per regulatory guidelines, fund transfer can only be made from your own linked bank account.

If you make a payment into your beneficiary bank account using a bank account that is not linked with Kotak Securities Neo, the amount will get refunded to the same bank account by the same method that was used to deposit and you will not be able to avail increased limits to trade. The turnaround time for this refund would be on the basis of the mode of payment used by you. If you use IMPS or RTGS the refund to your account will be immediate, however, for NEFT this may upto 2-4 hours.