There's no manual mode per se with something like a quadrotor, even a simple one requires really unintuitive applications of thrust to affect things like yaw. You could fly one in 'rate' mode though - where the stick deflection commands pitch/roll/yaw rates directly.
Unlike a 172, it's pretty unstable flown like that, and most people would turn such a craft into a smoking crater shortly.
When you are flying a quad with a lot of power, it is fun to zoom up vertically, cut the throttle, and drop.
Normally, the motors have enough power to arrest the fall before you hit the ground but if you get into VRS no amount of power will save you.
If you realize you are in VRS before it is too late, apply forward thrust and fly out of it.
I have "several" quadcopters. I don't actually know how many I have at the moment, but in addition to enough components to fill a couple of five-gallon buckets, the three I use most regularly are:
* an Autel Evo 2 Pro * a 5" FPV quad * a 3" FPV quad
The Autel is a dedicated photo/video quad. It's stupidly easy to fly, to the point that I can put the controller down and come back 20 minutes later to find that it hasn't moved.
I use the 5" for fun, mostly freestyle stuff. The 3" has enclosed props and is intended for videography. Neither of these have GPS. While they do have flight controllers, they are optimized for minimal input latency and do not attempt to automatically keep themselves upright whatsoever. Flying them is much like balancing a dinner plate on top of a broomstick; it requires constant input adjustments. That's difficult at first, but after ~20 hours of practice it starts to become unconscious. I've been doing it for a few years now and really don't even think about it anymore.
Prior to the availability of ARM STM32-based flight controllers, I believe there were some fully analogue solutions out there that allowed similar flight characteristics.
At the most detailed level, all of them are sending a PWM signal to each individual motor. Controller input is translated from 4 axes (pitch, roll, yaw, throttle) to the appropriate changes in the PWM signal for each motor.
I _think_ I could probably set up a fully manual quadcopter and get it to fly predictably without a flight controller, by using the radio receiver on the quad to output PWM directly to the individual motors. I'd have to set up the controller so that input on each axis is "mixed" appropriately to the respective per-engine output channels. The result should be (barely) controllable. I bet wind and the dynamics of lift would be much more difficult to deal with, but I think it'd be doable.
Is that "manual" by your definition?