LinkedIn is great. You'd be surprised how many welcoming people you'll find if you communicate like a real person. But be prepared and don't take personally when someone ignores you or give a bad response. Just move on.

Do extensive research first and make sure there is a real potential that what you offer can be valuable to them. And communicate that. Smaller businesses are much easier to sell to. Startups are even easier, but you have to be sharp, deliver very quickly, and be prepared for a more dynamic environment.

I've sold SWE services as a solopreneur to customers in the US, UK, even Hong Kong. All through direct messages on LinkedIn.