Sorry for the delay in response.
Good question. Yes you can do down and up strumming and down and up picking of individual notes.
Using down strokes and up strokes is very important when you want to start playing faster.
If you only use downstrokes (in either strumming or playing notes) you’ll fairly quickly hit a speed wall of how fast you can do that.
By using the upstrokes as well you essentially double the amount of notes you can play with the same amount of right hand movement.
If you still have questions let me know.