In PyMOL 2 and newer, loading a new PDB file will automatically display molecules in cartoon mode. There are 10 cartoon modes available in PyMOL (mine version 2.3).
The 10 modes are: arrow, automatic (default), dash, dumbbell, loop, oval, putty, rectangle, skip and tube.
Using ubiquitin 1UBQ as model to display 9 of 10 cartoon modes (cartoon skip is not shown, as it “skips” cartoon).
default mode: automatic