Look for Coworking and Coliving spaces but also Selina locations and whereever RemoteYear as digital nomads destination is around the world and you will find hotspots. Also sites like Nomad List can help.
Also (Kite-) Surfing and Scuba Diving seem to be popular hobbies with nomads, you will always find nomads at hot spots (like Mexico, Spain, Thailand or Egypt).
From my experience:
Chiang Mai, Thailand <- probably #1 worldwide
Bali (Canggu/Ubud), Indonesia <- probably a close #2
Koh Phangan/Koh Lanta, Thailand
Da Nang, Vietnam (but also HCMC/Saigon)
Colombo, Sri Lanka
Cape Town, South Africa
Dahab, Egypt (though technically Asia because it’s on Sinai)
(Las Palmas de) Gran Canaria, Spain (and Tenerife)
Playa del Carmen, Mexico
Mexico City, Mexico
Panama City, Panama
Rest of the World
There are not a whole lot of nomads in Australia, New Zealand, the Pacific Islands or Caribbean, mostly because either expensive or far away from the rest with a bad internet connection. That said, Bermuda has just announced a DigitalNomad Visa. And probably not a single nomad in Antartica 😉