What is TWRP

Team Win Recovery Project (TWRP) is an open-source software custom recovery image for Android-based devices. It provides a touchscreen-enabled interface that allows users to install third-party firmware and back up the current system, functions often unsupported by stock recovery images.
It is, therefore, often installed when rooting Android devices, although it isn’t dependent on a device being rooted to be installed.

How to Update to the latest version of the TWRP on any Android without PC

Step 1. First of All download the latest version of TWRP for your mobile, It should be in .img format.

Step 2. Reboot your mobile into recovery mode, method of rebooting in recovery vary from mobile to mobile, generally it’s press and holding power key and volume up key simultaneously.

Step 3. In TWRP recovery Press install.

Step 4. Now to the install image button, which is at  bottom right corner of the screen.

Step 5. Locate the latest version of the twrp file, if you downloaded it from your mobile then it will be in your  download folder.

Step 6. Now click on the twrp file which is for example (twrp-3.2.1.img)

Step 7. Now select Recovery partition and swipe to confirm flash.

Step 8. You are all set, your recovery version will be update to the latest version of TWRP.