Short answer would be no. I'm assuming this is a renpy game which the aspect ratio gets set by the dev when the game is first made. Since the majority of monitors use a 16:9 aspect ratio this is the ratio that gets set and which all the assets in the game are made for. Your monitor appears to not be 16:9 which means if it tried to completely fill the screen it would have to either cut off the sides of the image which would mean you'd miss out on anything in those parts or it would stretch the image which would make it look terrible. I think the only way for you to be able to see it fullscreen without bars would be to use unren and manually change the aspect ratio yourself but you'd likely end up breaking large parts of the game by doing so.