The edits are saved on your device and when you reconnect with the data, the modification is saved to Google Drive. Here is the guide detailing how you can edit Google Docs offline on your Desktop PC browser or mobile app.
Steps to Open and Edit Google Doc Files Offline
Here are Simple Steps to Edit Google Docs File Offline on your Chrome Browser without WiFi or Internet.
How to Make Google Docs Offline on Mobile?
You can also make the Google Doc files offline on Android and iPhone mobile apps. All you need to do is, click on the three-dot menu option and click on make available offline. Also, you can make recent documents automatically offline using a settings option. That’s it with this Simple Guide, you can make your Google Docs, Google Sheets and Google Slides files offline on Google Drive for editing without the internet.