Part 1 of of the goodies to drop on the install of Elementary OS.
Update the elementary OS
sudo apt update
sudo apt upgrade
Install gdebi if you need a GUI
sudo apt install gdebi
For watching videos I like VLC
sudo apt install vlc
Elementary OS commes with Epiphany web browser, so firefox it is. Although I DL Brave deb later and installed.
sudo apt install firefox
Install archive formats (your never know)
sudo apt install rar unrar cabextract lzip lunzip arj unace p7zip-rar p7zip