Question

If I learn to play say an alto saxophone, could I potentially play all other saxophones with the same key?

Answer 1

Yes.

Step-by-step explanation:

All saxophones share the same fingering. So you can indeed play all saxophones after learning alto sax.

Alto sax & baritone sax are both in Eb.

Soprano sax & tenor sax are both in Bb.

Answer 2

Yes you could you could always talk to a music teacher or someone who has done the same