Garage/Basement Party Room

Not right now or anything, as I know it's going to take a long time saving money for it, but I wanted to add a garage & basement to my house that serves as a party/theater room. I think the cost will be high, especially considering my home is, I think, built on a concrete slab, but yeah. I want my current garage to extend with a ramp downward into a bigger garage, solely for the purposes of having an exit to said garage from the basement room. I’d mainly want it a bit larger just so I can drive my car into it and turn it around to drive back up the ramp exit. From that garage, I want a door that goes into the new basement room, serving as both entry & exit as I said. The basement/party room, will be one GIANT room that spans the length & width of the entire front yard/house/backyard from one corner to the other (garage aside) of the property. I’m talking, one huge room, with a high ceiling, water proofing, sound proofing, potential pest proofing, egress windows if needed, quality lighting, insulation, air circulation, & whatever else is recommended, all with the utmost modern quality possible to suit living in/having guests in. Everything else would come in as it goes, although I might want a kitchen/bar & bathroom potentially, with the kitchen still as a part of the one big room still. I'm not good at designing, but would appreciate the help.