So I did a bit more digging on this, and for VST3 plugins, you have the EditController::setDirty() method (https://sdk.steinberg.net/viewtopic.php?f=4&t=313), that can be used to do just that.
I’ll have a look to see if there is something equivalent for AAX.
Question for the Juce team, how can I invoke VST3 methods from my AudioPluginProcessor instance ??