u can ofcourse find stores that have pre-packaged stuff, usually bigger or richer groceries stores. other places u can get the exact quantity you need in either a bag the shop offers or one u bring. bringing urs is better if possible for like jars and stuff so u dont have to then spill or deal with filling later.

what i prefer is going to a flour mill directly and getting the exact milling i want of the flour. same goes for meat, spices/herbs, dairy, u get the best if u go to the shop of the farmer or butcher or miller directly. never lived in an (urban) place that didnt have them in like 10-15 minutes distance at most