[Multiplayer Advanced Session] Query: Auto-Create sessions?

Hello community! I’m starting in the world of video game development, I already have a game project I’m working on, I wanted to ask the following:

Do you know the command for sessions to be created automatically? That the player does not create a session, just that he searches and when 20 or 30 players are searching, an automatic session is created

Excuse my English, I use the translator, if you can’t understand me well, let me know so I can write better

I don’t remember a single command to do that…
what I think could be possible is:

each player creates a session right before he search for one’s… that happens automatically when a “Search Session” Button is hit.
Within the Search Results, the own Session is ignored and not listed.

When a Search Result is chosen to be joined, the current session will be deleted first and than joined the Result one.

When the Player Leaves the Search Window, his current Session is destroyed, too.