You are confused about how alignment works.
Alignment process starts with the steering wheel perfectly straightened, then measurements are taken to validate that the wheels are, in fact, angled correctly on all 3 axis: toe, camber, caster.
If something is off, toe is easily adjustable. Camber and caster are harder, and adjustment options vary by model.
Steering angle sensor is not touched, nor does it need to be re-calibrated.
You don't just randomly point the steering wheel at some direction, re-align the wheels to that steering input (usually not possible, anyway), then reset the steering sensor, and then drive around with the steering wheel off-center.
You don't need to do that.
Bad advise, with a dose of FUD.
Warranty is not effected by taking your Tesla to an independent tire or alignment shop.
The ONLY place I would allow to touch my car's alignment are local independent shops that do it for a living. Any dealer's service center (SC), including Tesla's, does this once every blue moon, and is highly likely to do so half-assly. And over-charge you on top.
Tesla SC's are to be avoided for many reasons (search this forum), unless you know your service will be covered under warranty. Alignment will not be.
There is nothing magical about Tesla's suspension, especially on Model 3's.
Model 3's have plain vanilla independent suspension on all four corners, same as any modern car.
EV drive-train does not factor into suspension work considerations.
HTH