Where the paid Shopify work is

A great many people set up Shopify stores by installing a theme and changing the colours. That work is competitive and poorly paid. Theme development is a different market.

What merchants actually pay for. A store that looks like their brand rather than like a template. Custom sections a merchant can use without a developer. Performance work, because themes are frequently slow. Integrations with local requirements. And fixing what an existing theme does badly.

The commercial position for somebody in Pakistan. Shopify merchants are overwhelmingly in America, Britain, Australia and Europe, they pay in dollars, and they need work continuously. This is one of the more reliable routes into international freelance income for somebody with front end skills, and the barrier is learning one platform properly rather than competing on general web work.

What you need. HTML and CSS properly, JavaScript, and Liquid, which is Shopify's template language and which takes a week to learn if you know any programming.

What you do not need. A backend language, because the platform handles the commerce entirely, which is why this is accessible to a front end developer.

Two kinds of work. Custom themes built from scratch or from a starting theme, which pays best. And customising an existing theme, which is most of the available work and is where to start.

Learn the platform's own conventions, because merchants and other developers expect them and work that ignores them is harder for the next person.