An easy-to-use Envelope Generator with adjustable times and shapes for Attack, Decay+Sustain and Release.
This is a Processor Rack preset. First save it, then add it from the list of Processor Rack presets.

Connect to the MIDI To CV Gate signal and compact the rack.

To use it as an Amp Envelope, add a Processor > Amp module, set its volume to minimum and modulate it with the output of this module.