Interesting idea but I've not seen any one purposefully do this before. Pretty sure the genetics will determine above all and it'll finish when it wants to finish. If anything I would think stressing it will cause it to flower earlier? Not that topping and such is very stressful on the plant if done right, but I don't think it'll extend veg time. Better to focus on good strong growth, maximize light and VPD and perfect grow conditions I think.
I won't weigh into the pros or cons of autos lol, good genetics is good genetics, bad is bad, doesn't matter if it's auto or photo as far as I care. Ive grown good autos and bad, good photos and bad. The finished product is all that matters.