Of course you can! You can enjoy all our content without being connected to Internet (Wi-Fi) or 3G/4G/5G.
First you need to download the content/games you want to download to your device. In order to do it, ensure you are connected to a Wi-Fi network or you have 3G/4G/5G, and tap the bottom right "download" arrow icon on the content/game you want to download to your device. That's it! From now on, that content/game will be in your device, ready to be used without Internet, Wi-Fi or 3G/4G/5G.