Minimize or maximize w3m

W3m is console text browser, to minimize w3m use ctrl-z, which stops w3m. Then use bg to put it in background.

Now to bring it back to foreground or maximize it, you need job number w3m is running. bg will also list and assign job number to the task it is putting in background.
Now use fg n to bring a job to foreground, with n being the job number, example: fg 1

Alternatively you can use top or htop to view jobs running in background or their job numbers.