Can use commands:
$ sudo apt update
$ sudo apt list --upgradable
Or commands:
$ sudo apt update
$ sudo apt upgrade --dry-run
Or commands:
$ sudo apt-get update
$ dpkg --get-selections | xargs apt-cache policy {} | grep -1 Installed | sed -r 's/(:|Installed: |Candidate: )//' | uniq -u | tac | sed '/--/I,+1 d' | tac | sed '$d' | sed -n 1~2p