How do real estate agents actually find serious buyers online?

I’ve been noticing something interesting while browsing local groups and forums.

People often post things like:

“Looking for a 2BHK apartment in [city]”
“Need a rental near [area]”
“Searching for a house under [budget]”

These posts appear in a lot of places — Facebook groups, community forums, sometimes even Reddit threads.

It made me wonder how real estate agents usually capture those opportunities. Many agents seem to rely mainly on property portals or ads, but there are clearly buyers talking about what they want in public discussions.

For agents or brokers here — do you actively watch for posts like this, or do you mostly rely on listing platforms to generate leads?

Just curious how people in the industry usually handle it.