Some other DAWs have a cool feature to gradually Slow down a selected audio event by having an option to change the fade-out from controlling the volume to controlling the speed of that event.
The cool of that, firstly its straight forward,
and secondly, the event remains on its place, (for example, if the event is 2 Bars then when they slow it down with that feature it remains as it is 2 bars).
can we have something like that
Add the feature-request tag, please.
Myself I would be against it. If slow down should appear in Cubase I would definitely prefer dedicated controller.
You could try to use the following technique, even though it will update the events length in the project view:
Audio → Processes → Pitch Shift
Step 1. - Red - make sure to select the Envelope
Step 2 - Orange - make sure time correction is NOT activated
Step 3 - green - set the pitch shift range to something that will work for you; you can set it all the way to 48 semitones, which ought to be enough to create the stopping effect
Step 4 - not marked - set the pitch envelope to your liking