Is it or will it be possible to increase the max player amount?

for an roleplay gamomode we need more possible players than 30.

that’s the cause of my question: will it be possible to take more than 30 players on a server?

You can set it to 32, but it is known to cause issues. Currently, the highest player limit (that maintains server stability) is 30.

They do intend to increase this, which you can see here https://fivem.net/#24-slots

Don’t waste your time while you are waiting for the extension of player limit. Get your gamemode more ready than it currently is.