So the max trainer level is 40, but say you are level 15 then the highest level your Pokemon can become are 15 (max level a Pokemon can become is 40). Every time you power up a Pokemon it gains half a level. But even saying this the answer if every Pokemon will get to it's "Max CP" is no. There are IVs (Individual Values) in this game from 0-15 which give Pokemon of the same species that are 15 IV a boosted CP over the average 7-8 IV Pokemon. So no not every Pokemon will become max CP in that sense.
GamePress
Will all Pokemon reach their "Theoretical Max CP"??
I noticed that my Vaporeon's CP ceiling keep raising as my trainer level goes up?