Yes. In neurons, once the membrane reaches threshold, depolarization is an all-or-nothing (all-or-none) event: voltage-gated sodium channels open in a regenerative cascade and a full action potential is produced, rather than a partial spike scaled to stimulus size.
Subthreshold stimuli do not trigger that cascade, so no action potential fires. Stronger-than-threshold stimuli generally do not make a larger spike; instead, stimulus intensity is typically encoded by how frequently action potentials fire.