Yes, just turn off autosave from the beginning of the game and then you can save right before you select your starter and then turn the game on and off until you get the nature you want.
As for using autosave, personally I don't but that is a personal decision based on what kind of play style you have.
Thank you, I've not really played around the autosave feature for my first play through on Shield but thought it'd be nice to try and get an ideal natured starter for Sword play through.