In Chordle you can search several song sites directly from within the app, allowing you to import songs you find there into your song library.
First, switch to the online search pane, select one of the supported sites and enter the title of the song you want to find:
Click on the search result that you want to use to preview it. If you are happy with the song as a starting point, click Create a Chordle song from this:
You can tweak the song content before saving it using the edit song screen. After saving, the song is added to your song library, and you will be able to find it there going forwards.