Some streaming platforms also provide subtitle options. For example, if you watch 'Solo: A Star Wars Story' on Disney + (assuming it's available there), there should be subtitle settings where you can select the language you prefer for the subtitles.
Another option is to check the Blu - ray or DVD release of the movie. Usually, they come with subtitle options in multiple languages. If you own a copy of 'Solo: A Star Wars Story' in either of these formats, you should be able to access the subtitles directly from the disc menu.
You can try to look for the subtitles on official movie subtitle websites like Subscene. Sometimes, they have a wide variety of subtitles for different movies, including 'Solo: A Star Wars Story'.