Not all handlebar bags that you can find for sale are universal. That is, not all of them can be installed on any handlebar. However, for practical reasons, numerous manufacturers have started to produce and distribute models that come provided with a universal mounting system.
To be sure that this is the case with the bag that you like, it is a good idea to take a close look at the specifications of the said product. If the description of the item does not contain sufficient info on the matter, it is advisable that you contact the manufacturer and that you ask for more details.
Besides, you can also go on biker forums and ask fellow riders about their opinion on the model that you like. This way, you will get first-hand reviews of the said handlebar bag. When it comes to the installation process, it should be added that most of the choices that you can find online are simple to set up.