I have some blueberry bushes of different varieties that were planted this year, and was wondering if I could effectively/safely spread branches of blueberry bushes so they naturally puff out more in future years.
There is a significant difference between fruit trees like apples and bushes like blueberries
Tree branches of young trees get trained in a certain shape and sometimes position, because the main branches will form the base structure of the tree for as long as it lives, pruning of adult trees mostly maintains that structure and keeps the tree productive.
Bushes send up new branches from (near) the base every year and for continuous productivity, older branches that bear only little fruit get thinned out to make space for younger, more productive branches. For your blueberries, that means that after a few seasons you will start selectively removing the oldest ones. (Pro tip if you are unsure: mark non-bearing old ones during summer with a ribbon or similar.) The rule of thumb which canes should be cut and when differ between types of berries, so do your homework. Further training isn't necessary, except removing the occasional dead branch after a hard winter or perhaps if a branch really gets in the way. The bushes will spread out a cording to their natural growth habit1.
1 Note that the natural shape can differ between cultivars, I have blueberries that are "tall and lean" and others with a more "short and stocky stature".