As @loudouncodes mentioned, no easy way but to network and to market yourself. But you also need to consider which aspect of yourself you want to sell as the side gig.

* Would you write a book to impart your knowledge to the readers?

* Would you sell your physical hours in delivering work products?

* Would you sell your advice via consulting?

Many ways to cut this fruit, and still have it taste good. Best of luck on your ventures.