You can manually for all of them but the method depends on which sheet you are using.
There are
5e Shaped
5e OGL
5e Community Contributed
For the sheets
5e Shaped - Just select Custom at the top in edit mode and fill in as needed. (Artificer and Revised Ranger are nicely included)
5e OGL - Go to the gear tab and down to custom class
5e Community - Nothing is really built it so just write it in as needed.