Notice period increased unilaterally by Company - they changed the notice period to 3 months

I joined a construction company in Jan 2022. While joining, the notice period was mentioned in the appointment letter for 1 month.
Suddenly, the company raised an Updated HR Policy amendment for separation. For my grade, they changed the notice period to 3 months.

Now I have received a good offer from another company, but they need to join me in 1 month, so can I give the resignation with 1 month's notice period and leave because as per the updated HR policy document have to serve three months notice period, not agreeing to the same will consider as non-complete exit process and threat of legal action. Am i bound to serve the same as i have received some suggestion from google that " The employees would only be governed by the agreement which was executed by them bilaterally. Extension of the notice period by your employer unilaterally is illegal and cannot be enforced. Legally, you are only bound to serve 1 month's notice, which was agreed by you during joining. There would be no legal infirmity."

Kindly suggest to me the correct solution & way to deal with this.

Legally the terms and conditions can be changed only by giving a notice of change following section 9A of the Industrial Disputes Act. But an employee who is not a workman (which will cover all employees who has no managerial powers like sanctioning of leave of subordinates, initiating disciplinary action against the subordinates, appraising the performance of subordinates etc) is bound to follow the conditions made during the employment also. As such, if you are a manager (not merely by designation but by functions) and the notice period was revised and communicated to you, you should follow the revised one. At the same time, if not a manager, you can challenge the notice period. You should have challenged it when the communication came. Another legal provision is that in respect of employees who are under the scope of Industrial Disputes Act, notice period of even one month will not be maintainable since the worker is not liable to give notice to leave an employer even though an employer is liable to give it when he terminates and employee.

As Madhu has rightly pointed out, you have not mentioned your cadre. Are you a Manager with subordinates reporting to you or you are merely an employee?

If you are a Manager with subordinates and if the change of notice period from 1 month to 3 months has been communicated to you, you will be required to follow it.

A seasoned employer, always amends the policy after communicating it to employees in writing and obtaining their acceptance.

Regards

MVK