You can do this by tapping the Settings app in your Apps list. Emoji support is dependent on the version of Android that you are using, since emoji is a system-level font. Each new release of Android adds support for newer emoji characters. On some devices, you may need to tap the "System" category first. Some Android devices will require you to enter this additional menu to view the Android version. You'll see the "Android version" entry. The number indicates which version of Android you're using:   Android 4.4 - 7.1+ - Devices running 4.4 or later can use the Google Keyboard to add emoji. Your device's built-in keyboard likely has an emoji option as well. Character availability and style are determined by your Android version.  Android 4.3 - You can enable the iWnn IME keyboard to type black-and-white emoji characters. You can also download a third-party keyboard to insert color emoji characters.  Android 4.1 - 4.2 - You can view certain emoji, but there is no built-in keyboard option. You may be able to use a third-party keyboard to type emoji.  Android 2.3 and earlier - Your device does not support displaying or typing emoji.

TL;DR in Vietnamese:
Mở Settings (Cài đặt) của thiết bị Android bằng cách chạm vào biểu tượng Settings trong danh sách ứng dụng. Kéo xuống cuối trình đơn Settings. Chạm vào Software version (Phiên bản phần mềm), nếu cần. Tìm phiên bản Android.