In my teenage period (1950s) making out was 'going all
the way.' Sometime since, making out has come to mean
petting (groping, touching, fondling). The word
petting seems to be vanishing in the 21st Century.
Before grandfather and grandmother married, they had
sexual intercourse (fucked) in their teens but that sounded so
harsh, so they called it making out.
Today, making out is just fooling around, groping, and touching, but not having intercourse.