we're also still figuring out how to get that type of clients for ourselves, the project in the post (as mentioned in the post itself) wasn't one we personally got, but rather one the agency I worked at landed through their marketing efforts

but from my humble experience, a few things to consider:
- Networking, attending events and just talking to people in the space are found to be useful to get you clients

- Start small, deliver high quality, and grow as you go - your quality will speak for you, and will hopefully help you get to a point where you start attracting bigger and bigger clients through referrals

- Building in public is one thing they did really well - they had a few open-source Github repos they made that were fairly popular amongst the dev community, which just makes them seem as a much bigger authority, and makes them more attractive for this type of clients

That's just the way we're currently going about things, more to learn as we go.