I am on notice period and My HR clearance is done. I am doing wfh not going to office. Will they extend my notice period??????

They can do anything...

Will they do depends on their mood

Notice period can never be extended as it comes under the legal lens. The only scenario when it can be extended, is when you take leaves like EL or FL. You can take approx 6 days of sick leave across 3 months with no impact on your NP.

Nope

No