That should be the idea, but the brand has requirements. When you go to a McDonalds and order a burger you know what it will taste like. The reason you know that is McDonald's requires all franchises to do quality control. I don't know the exact arrangement, but probably the franchise is not allowed to source their raw materials elsewhere. If a McDonald's burger doesn't taste right they will take action up to taking away your franchise rights - I've never heard of this happening, but they have the right to protect their brand in this way.
When you buy a franchise you get a territory. You know you will not have to compete with anyone else. If the brand thinks it would be good to have a store a few blocks from yours they will either offer you the new store first, or give you a guarantee that your business won't suffer for the competition.
While there is risk, if you buy a franchise and work hard it is a path to a nice life. You won't become richest person in the world, but you should be able to get to upper middle class. The first 30 years are mostly paying the bank though, so be prepared for a long term investment (but after 30 years you can sell your franchise and get the equity back - enough to retire on).
Note that I started with should. Some franchises are better than others. Some will try to sell you a bad territory where it is impossible to live on the earnings. Some will force you to buy (sell) product that your customers don't want. It can be a good deal, but it can also be a ticket to bankruptcy.