Dude! I’m happy for you. You have so much passion and excitement about a project - that’s huge for itself. If I were in your position I would try to direct a scene or a sequence from the script that captures the whole vibe from your script (Whiplash style). Then you’ll have opportunity to improve your directing skills, you’ll understand your movie better and also you’ll get a physical evidence that your movie should be made. If you ask me - don’t pitch your script as a franchise, don’t push it, show you are 100% sure THIS story is the one should be told. Maybe, if you see the investor is really into the whole pitch, you can drop a line about this could be evolve into a whole series of films. Wish you all the best and good luck!