There is a nexus mod you can use that makes it so your in a session with only friends but because this is using a mod online, it can result in you getting banned. I wouldn't risk it because of that. I mean we can keep pestering Rockstar to add the option to have invite-only sessions like in GTA online but at this point, I don't know if they will add it. I think if the game does come out for the Switch 2 though, they might end up adding it. Fingers crossed they do it for all consoles and PC though.