Check my theme is Shopify 2.0 OS

Online Store 2.0 is a set of features and feature improvements that make themes and theme apps easier to build, more flexible, and easier to maintain.

Many Online Store 2.0 features rely on JSON templates. You can migrate a theme's templates to add support for these features by converting a Liquid template into a JSON template, and moving any required Liquid code or HTML into sections that you can include in the new JSON template.

Thus, the most obvious sign of Online Store 2.0 is the file structure. Template files are located in the templates directory of the theme:

Files structure

That is the basic sign to determine if your theme is a Store Online 2.0 theme.