For Classic Mode games, you will be able to select the language of a game before it starts. To do this, once you select this game mode, you must click on the icon at the top of your screen represented by a gear.
Keep in mind that the language will always be determined by the user who created the game. For this reason, you may receive invitations to play in languages that you do not normally play in; if you prefer, you can decline the game and continue playing in the language you want.
We invite you to visit the article: "How can I reject a game?"