How to create fake meetings in Jitsi?

There is a need to create multiple fake meetings in Jitsi in order to test logics in our set up. The meetings does not need to contain any participants, just that prosody holds a list of active meetings.

If possible we would like to create 100s of meetings

Is this possible?

There is no such thing of creating a meeting. The first one to join creates the meeting ( a xmpp muc - multi user chat) and the last to leave will destroy it.
So in order to have an active meeting you need a participant in the meeting. So you need to create participants and keep them connected.
You can use selenium to load page. Or you can use any xmpp tool that can use websocket or bosh connection.

Take a look at Puppeteer With some developer knowledge, you can utilize this library to spin up meetings on your server and join them with multiple fake audio and video streams (--use-file-for-fake-video-capture & --use-file-for-fake-audio-capture). This will also allow you to join in-progress test meetings to observe the meeting quality.