Does google ads support localization by default? Lets I am running ads for clients located in France and Germany. Then once campaign is ready will google show ads in German and French language? or does it depend on user's default device language?

With google, you should try to change language at Google Account setting: https://myaccount.google.com/language

But by default localization is not done by google is that correct?

sr, I don't have much experience with GAds but in my experience, most Google Products follows the Google Account language setting, I have done this for my users

@Aditya - Google ads will target language automatically. It might take a bit longer for the machine-learning to realize that German/French speakers are more likely to convert with your ads, but it will learn it eventually and then target them. It is recommended to not set the language yourself. Source: Personal experience; I run ads in Luganda (Uganda's official language) which isn't even recognized by Google

@Lak Thanks got it