Language preview

Theme settings > Language preview

First, you have to duplicate your current theme to use for 2nd language

Copy a preview link of the 2nd theme

Go to Navigation > Create Language menu. Then paste preview link for 2nd menu

Show the Menu on Header of the original theme. Go to Theme Setting> Language Preview

Now go to Customize the 2nd store then translate the text

This way is not the perfect solution because you can not translate the product, blog, page so we do not recommend, if you need a perfect solution so we recommend using the third-party app like Weglot.