the canonical way is reaching out to anyone in your work history that you had any sort of positive working relationship with. i just went through this exercise and saw a tip in a similar thread to ask something like this in the email, “do you know anyone who is looking for contractors?” this way you don’t create a potentially awkward situation for them where they have to say they can’t hire you. and, in my case, this led to referrals that ultimately ended up in signed contracts.
there are sites online, like the whoishiring threads here. i’m running https://hourly.fyi/jobs/