Hello Subhajit,
Their no URL shortener available OOTB in Campaign yet but I do know there is an Enhancement request raised for the same to integrate with bit.ly but it has not been added yet in the product.
You can still use any URL shortener in SMS deliveries , the only limitation is the tracking will not be present for such deliveries . So if you are okay without tracking data present for SMS deliveries , you can still use any shortened URL .
But , if you do need tracking enabled for shortened URLs , it is still not functional .
Regards,
Adhiyan