How to get projects as a backend developer?

Hey guys I am a developer (tech) with 5+ years of experience in many well known companies - where I built some really cool things.

To build a showcaseable portfolio, I have been working with NGOs for free since a few months.

Now I want to start getting some paid clients. How can I start approaching hospitals, banks or even governmnt organizations and help them build their websites, apps, or any software? I currently don't know anyone from those domains

Does anyone have any clue of how do people get such projects?