I am a commercial grower of stevia plants and consult on commercial plantations globally.
There is virtually no point in growing stevia plants at home except for decoration or if for some crazy reason you like the taste of raw stevia leaves (anis / liquorice).
Additionally, the chance of you acquiring a cutting (seeds have an extremely low germination %) that is of a high "sugar content" is very low. Odds are you would get your hands on a Chinese variety that was really use medicinally in teas.
If you want to cut sugar out of your diet head to a good grocer or health food store and purchase stevia powder, but beware, many of the cheaper ones are cut with aspartame, sucralose, rice powder, etc. Also, the cheaper the powder the higher the odds of having a poor aftertaste. Remember, insanely sweet so you only need a pinch in your coffee, etc.
If you are a soda drinker and want to cut it out, find Zevia in your better grocery stores.