Hey, I want to develop a microsite for my primary website on which I can sell some different items with different overall theme. That should have the subdomain before the main domain. (example :- https://subdomain.domain.com). Any ideas how can I do that?

You need to create a new website setup record, and then a new domain

Can I do this with subfolders or subdirectories? https://www.domain.com/XYZ where XYZ is an entirely independent website. like the country versions of sites happen. www.BRAND.com/cn or www.BRAND.com/in . the end path takes us to an entire independent site while being on the same domain..

anything after the .com is not considered a new domain, so no - you won't be able to set up a new website record for it or activate extensions against it

okay then, if I choose the first one I will have two hosted sites.

Correct

Thanks, I have read your blogs. they are really helpful.

No problem