Lock-in period applies to the time period from which you are unable to withdraw funds from a mutual fund.
The majority of mutual funds do not have a lock-in date. Open-ended mutual funds are what they’re called.
Closed-ended mutual funds, on the other side, have a predetermined lock-in duration.
Furthermore, while ELSS or tax saver funds are open-ended mutual funds in essence, they have a three-year lock-in duration from the date of purchase.