What visa for internship.

Your best source for information would be to contact the US Department of State. There are different kinds of Visas for different uses. I think the J-1 Visa is for foreign college students to come to the US to gain practical work experience. I'm not sure the J-1 Visa is the document you are seeking because I don't think it applies to minors who are in high school.

Here is an excerpt of what the J-1 intern Visa requirements are

J-1 Visa Intern Program

These programs allow foreign professionals to receive training in their occupational field in the US.

Interns must be foreign nationals who are currently enrolled in a foreign degree or certificate granting post-secondary institution outside the US or who graduated from such an institution no more than 12 months before his/her program’s start date. Participants must be at least 18 years old, and must have their English skills evaluated or verified by a recognized English language test, by signed documentation from an academic institution or English language school, or through an in-person interview conducted by the sponsor, or by video conference or webcam.

Perhaps someone on here who is an Indian High School student who got a paid internship offer could give you some advice.

There are 4 US Consulate offices in India and here is the link to their contact information, including street addresses and phone numbers in India. I'm not sure you will get all the help you need over the phone but try that first.

https://in.usembassy.gov/embassy-consulates/

Good Luck