One sort of shortcut way to bootstrap this is to find people who do consulting in an adjacent area and partner with them...offer them some incentive to make the introduction, or allow them to be the middleman for a cut until you're more established. That could be something like a back-end expert partnering with a successful solo front-end expert. Or partnering with a successful solo non-software-dev consultant (design, project management, pitch decks, cybersecurity, whatever).