There is no explicit SetLatency() in the VST-3 spec.
There is, however, a restartComponent(kLatencyChanged) possibility.
But this is only if the algorithm of the plugin changes while it is active (eg. the user changes a “mode”).
If the latency is fixed for a given sample rate, there is no need for the plugin to call this function
(the host queries the delay to the plugin, the plugin does not have to notify it).
The VST-3 spec says:
If during the use of the Plug-in its latency change, the Plug-in has to inform the host by
using IComponentHandler::restartComponent (kLatencyChanged), this could lead to audio playback interruption
because the host has to recompute its internal mixer delay compensation.
WaveLab versions before 10, did not support plugin latency changes while the plugin was active.
When this happens now, WaveLab has to briefly auto-stop/playback, to take this delay into account.
In previous WaveLab versions, the delay was taken into account next time the user would restart playback himself.
Some link that might be useful for you: