Tomatoes are acidic, baking soda is alkaline, sugar is neutral. Adding baking soda to canned tomatoes will neutralize the acid but won’t change the taste too much (depending on the amount). Adding sugar won’t change the acidity of tomatoes but will greatly change the taste.

From my personal experience, adding sugar to a simmering tomato sauce for long enough that sugar caramelizes, will make the sauce way better.