Portrait vs Landscape Orientations in Linea
How do I create a sketch in a specific orientation? Can I change the orientation of an existing sketch?
Linea will create a sketch in whatever orientation your iPad is in at the time of creation. So if you turn your iPad to portrait and press the + button the resulting new sketch will be in Portrait or vice versa.
If you want to change an existing sketch's orientation from one to the other, simply open the sketch and then using a two-finger pinch/rotate, turn and re-orient the canvas to the desired orientation. Next, close the sketch. This saves the current setting for it and the sketch will then be re-oriented when you re-open it. You can do this at will to change a sketch from one to the other.
Finally, Linea comes with some pre-set aspect ratios besides full screen witch can be useful for certain types of sketching.
To get these preset canvas sizes press and hold the + button from the project view and you'll be presented with several options for custom canvas sizes including 16x9, 3x2, square and so on. Keep in mind that sketches created in this fashion CANNOT be changed later on. Once they are created (like in square format) they remain square format.