Not exactly. It is perfectly possible to make a part from scratch (I do it regularly.) To use the parts editor (which I rarely do) you are best to start from an existing part as it can not modify most parts of the .fzp file and needs to have a .fzp file which has the correct number of pins as a starting point. Part editor was not completed when development stopped in 2016 ( development restarted in 2019 but I believe the parts editor is still under development and a new one hasn’t been released yet. This tutorial is YouTube based and usually uses parts editor (and applies to current Frtizing versions which many of the others don’t):
I lately learned there aren’t links to the videos in Old_Grey’s tutorial so you need to do a google search for the title and then they come up on YouTube.
Your part should be reasonably simple (you need to start from an existing part which has 1 SMD connections though to get a correct fzp file with a SMD pcb file such as an SMD single pin header.)
Peter