It's better to move whole statements when possible. Like in IntelliJ.
There is little sense to move a part of statement or declaration.
I can see that people may want to move part of an expression/calculation. Or change order of arguments passed to a function.
Anyway, if there is move-line an move-selection, then it would be a matter of selecting to statement boundaries (which is not on my current list, sorry). Most people will not have more than one statement per line. So moving lines will do this in that case.