My main domain is targeted for India, Can I use my sub-domain to target throughout the world?
How can I achieve this?
This is no easy question and I think there might be many different ways to achieve your goal.
As Google itself suggests, it's mainly about your content and where it's shared.
It's going to be all about the content you put on that subdomain and in which countries your content is being shared (I'm not talking about social media here, but I mean links in articles, forums ecc..)
And obviously, the content on your subdomain should be in English.
PS: I suggest you to use another primary domain instead of a subdomain as I think it's harder to rank subdomains compared to primaries. Check this Twitter post from Giuanluca Fiorelli about moving a blog from a subdomain to a subfolder