I really like your enthusiasm.
BUT: you should really focus on familiarizing yourself with the Aircraft before planning RL flights.
Pick an airport, pick a random SID (they are in MSFS and you can just pick one), pick any waypoint that lies between departure and arrival airport and then pick a STAR that sort of makes sense. You can also google charts by just searching “LFPG charts” for example. Read them, try to understand what they tell you and pick a STAR in MSFS that looks similar. Simple as that.
And then learn how to use the Autopilot. from your question the other day I understand you don’t fully comprehend the A/p functionality of an A320. Try to get used to that first.
Afterwards you can worry about the SimBrief part. You are by no means supposed or obliged to create a SimBrief flightplan to perform a proper flight including the use of Autopilot. Especially that SimBrief does not necessarily give you the correct SID/Runway bc it does not always have the current weather. So a SID given by SimBrief is obsolete anyways for real life use sometimes. You can even select a cruising ALT that you want. Doesn’t matter how high, just pick one. Say 20000ft. And start flying.
The time you spent here asking questions could have easily been spent watching tutorials, flying around, try the functions and learn the Aircraft.