When you open Google Docs, Sheets, Slides, or Drawing, it will launch in a new tab or window in your default browser as long as you have an internet connection.
All Google Docs documents and sheets are actually not documents at all: these documents exist only on Google’s servers. There is no “google docs format.” The only way to get offline copies of these documents is to convert them into docx format.
If you are traveling or working remotely and find yourself in an area with no internet access, you will be unable to access these Google Docs documents. They need to be converted into Office format so they can be accessed offline.
The support note from Google is here: Google Docs.