Keep asking and it may happen:
Pretty please can we have level 5 in act 1?
Even better please no level capping by act at all...multi-class characters often lag behind compared to pure class.
While I prefer pure class characters in 5e for this reason, this is not a strict 5e rule set.
I find myself wanting to try some multi class combinations.
If your worried about the game being too easy, just add custom difficulty settings and features that automatically raise the level of adversaries according to player level.
This path will probably give you the best player satisfaction.
Sooo...Level Capping Sehr Schlecht!!!