Advance CoC is not ONE LEVEL based
powers of CoC go like this I assume
level 1 (base) : KO people after using 1 sce .... proven MANY TIMES
level 2 (base) : KO people after using CoC for a continuous amount of time / break objects around you ...
level 3 (advance) : put the environment under the influence of your Haki so you are able to change weather
level 4 (advance / once in every era) : manipulate space and time
p.s
levels 1 , 2 and 3 are proven and manga facts ... and level 3 on it's own is REALLY strong and level 2 can even be efftive on REALLY strong people as Shanks's CoC was effecting Jozu
one thing is clear ... Advance CoC exist and it's broken strong but for few people