I have dropped my iphone 6s and the screen got damaged. Still my phone in warranty period. May i replace it with free of charge?

Accidental damage is not covered under warranty. If you purchased AppleCare + then 2 incidents of accidental damage are covered but there is a service fee of $29 for screen damage or $79 for other damage. If you don't have AppleCare + then there is a $129 fee for screen damage: iPhone Screen Repair & Replacement - Official Apple Support

Ohm.patel1997 wrote:

no sir you not replace it .accidental damage is not covered under warranty. If you purchased appleCare + then 2 incidents of accidental damage are covered but there is a service fee of $29 for screen damage or $79 for other damage. If you don't have appleCare + then there is a $129 fee for screen damage. thank you.

Copying and pasting the answer given in the post before yours is poor form.