Sure, I can help you with that. YouTube itself doesn't provide a way to download whole playlists for offline use. However, there are third-party services that offer this feature. One of the most popular and legal ways is to use YouTube Premium.

Here's how to do it:

1. **Subscribe to YouTube Premium**: This is a paid service that provides several benefits, including the ability to download videos for offline viewing.

2. **Find the playlist you want to download**: Navigate to the playlist you want to download for offline viewing.

3. **Download the playlist**: Once you've navigated to the playlist, you'll see a download button under the playlist's title. Tap or click this button to download the playlist.

Remember, downloading videos outside of the YouTube app involves a potential breach of the platform's terms of service. Using third-party apps to download videos is against YouTube's terms, which state that you can only stream videos directly from its servers. Downloading videos is also a potential copyright infringement unless you own the video yourself, have permission from the copyright holder, or it's in the public domain.

So, it's always better to go with the legal way, which is YouTube Premium in this case.