Hi Nidhi,
Requirement under the Delhi Shop and Establishment Act
Sec 22. Leave
(1) Every person employed in an establishment shall be entitled:
(a) After every twelve months of continuous employment, to privilege leave for a total period of not less than fifteen days;
(b) In every year, to sickness or casual leave for a total period of not less than twelve days;
Provided further that a watchman or caretaker who has completed a period of twelve months in continuous employment and to whom the provisions of Section 8, 10, 11, 13, and 17 do not apply by virtue of an exemption granted under Section 4, shall be entitled to not less than thirty days' privilege leave.
(1A) Privilege leave can be accumulated up to three times the PL granted under law, custom, or award.
(2) The employer shall pay full wages for the period of leave due to the employee on termination or resignation.
Wages During Leave
Every employee shall be paid for the period of their leave at a rate equivalent to the daily average of their wages for the days on which they actually worked during the preceding three months, exclusive of any earnings in respect of overtime but inclusive of dearness allowance.
(I have paraphrased some of the information to make it easier for non-lawyers to read. You can always look up the exact wording of the section).
The act not only states that the company has to provide leave but also specifies how much and what type. It also details how leave salary is computed. The company has no choice but to follow it. If they do not comply, they are liable to prosecution, which only requires one employee to file a complaint, and they will be at your door.
However, it is not compulsory to create a leave policy. But it is compulsory to allow the leave required by the act. Nothing stops you from offering better leave terms.
Also, refer to Sec 24: Contracting Out
Any contract or agreement, whether made before or after the commencement of the Delhi Shops and Establishments (Amendment) Act, 1970, whereby an employee relinquishes any right conferred by this Act shall be null and void insofar as it purports to deprive them of such right.