I have purchased Macbook air 2020 through online 25 days back, can I exchange it with M1 chip Macbook air for free

Has the Mac you ordered been shipped? If not, you can cancel the order, receive a refund, and order the new one. If you received it >14 days ago, it’s too late – you’d have to sell it and buy the new one.

You have 14 days after your receive to return no questions asked.

No. The return period is 14 days.