Is it possible for hte Mavic 3 Classic to be used as a stabilized handheld camera and transition into flight in 1 shot?  Or does it always have to start and lift a few feet before continuing?

Example:  I want to walk through a house and out the front door and then end up about 30 feet in the air looking down. (drone propellers not spinning in the house, then starting and flying out of my hand for the end shot).

Thanks

If the motors are running whilst you are walking then the drone will probably fight you.
Ignoring tha, if your where to launch from a 'walking/moving hand' I would have concerns about the drone immediately trying to hold the postion where the launch was commanded ... unless you give it appropriate elevator or aileron. If you were walking forward and had the drone infront of you, you run the risk of walking into the drone etc. etc..
Risk aside I think it would be a tricky thing to do smoothly.

Yeah..  thats a given.  I'm wondering if there is a work-around to the drone not wanting to hold it's position and make it be fluid.

Try it and see.
The camera works just fine with the drone powered up before you start the motors.