Yes, Fly autoscales up and down depending on soft_limit entry defined in [[services]] section Do unused fly.io instances automatically shut down? (+ other region questions) - #2 by jerome
Autoscale up triggers in a minute or two in response to sustained traffic above the `soft_limit| threshold. Autoscale down is exactly its inverse, I’d imagine.
Btw, Fly engs are working on an improved autoscale solution apparently: Autoscale doesn't work - #6 by kurt