sharepoint online – show hide items in dropdown column based on another dropdown

I have two drop down columns A- state B-City. When Minnesota is selected I only want B- City to show the cities in Minnesota. I know I could do it by creating a MN drop down and using J query if A=MN show MN City Column, but there are a ton of states on here and even more cities. I have seen some jquery out there but I think I need a dummies version I cant figure out how they are pulling from A to get the B option.