How can the macOS calendar show (1 more...) daily events in the month view?
Two ways I can think of, if you don't want to (or can't) expand the window further…
Swap to Day or Week view - views are  Cmd ⌘   1  though  4 
Shrink the font -  Cmd ⌘   -  ( Cmd ⌘   +  to enlarge)