remote.co & remoterated.com are great resources.
Be careful with LinkedIn, there are a few towns in the U.S. named "Remote" which can confuse things π
I'd say join communities and try to zoom in on a specific niche for higher probability.
For instance, if you are passionate about music you can join a music NGO where there is plenty of people in the industry who will share/post jobs opportunities about marketing and the likes. Or network with musicians within the community who might need to hire marketing support contractors... I gave an example in music but this can work in different industry field too. Hope you find this useful.
Good luck with your search. I hope those links will help you find your dream job!
P.S. For what it's worth, I wrote this blog post to help you know what to expect from a hiring process in a remote company, and prep your material.
ComplYant