In a virtual synth patch, that is often done with an LFO whose intensity is set by moving the MOD wheel. Use the “Instr. MIDI Control,” assign the MOD wheel to one of its controls, and then use Renoise effects or automation to control it.
Alternatively, use Instr. Automation and control all of the aspects of the LFO and oscillator settings at will.
A VST sound generation is out of reach of any renoise action - it defines what it can do itself totally by itself. If it doesn’t have a vibrato option, you’re bummed but for workarounds.
One way could be to use the LFO device on inst midi control device on pitch bend, with sensible values.
If your VST synth is such a minimalistic beast, or you dislike tampering with the bend, you can still use a 100% wet chorus device on the VST output. Play with depth and frequency, you can automate depth to control the vibrato amount. This should work on any sound source, and should sometimes give smoother results than midi automation. If your VST effects the base sound with stuff like reverb or other effects, things are not so nice though, because the chorus device is after the reverb so it will vibrate too and sound strange.
If you were after pattern commands, you can pattern command any fx paramter, also the LFO or the chorus depth. If you dislike the default pattern data parameter values, you can stuff in a formula device to define better values or even kind of craft your own commands.
Ofc. these solutions aren’t polyphonic, so will affect all playing notes of that instrument or in that channel.
i have tried pitch control via an OSC, but the osc of renoise is too limited - to make good vibra it needs a higher range, maybe 10 times more ?
ig i know what you mean, if you mean you have linked the lfo to oscillator pitch in your vst. i don’t have this problem so much because i usually run renoise at x2 bpm or higher than default lpb or whatever (most people do, maybe?)
it still might be a good idea to try linking aftertouch/pressure or modwheel as suggested above and controlling vibrato inside your vsts.