For categorical variables, one hot encoding is a must if the variable is non-binary . But what about ordinals? These variables are ordered but are mutually exclusive. Do they require the same treatment as categoricals other than labelling?
The proper treatment of ordinal independent data in regression is tricky.
The two most common approaches are:
Treat it as continuous (but this ignores the fact that the differences in levels may not be similar).
Treat it as categorical (but this ignores the ordered nature of the variable).
The first method would not require one-hot encoding. The second would.
Some new methods have been developed. One that I have sometimes found useful is optimal scaling.