On a few occasions I have filed a departure procedure to a nearby
intersection just to get on top (comments section reads "IFR to VFR on
top"). After breaking out of the clouds and advising ATC of the bases
and tops, I usually cancel IFR and proceed "own nav" with flight
following. Which brings me to my question, if I cancel inside Bravo
airspace do I have an implicit clearance because I got there under IFR
in the first place, or is it common practice for ATC to give an
explicit clearance?

I ask because I'm a new instrument rated pilot and I'm pretty sure
both scenarios have happened to me recently. Thanks in advance.