Install Root,TWRP and Extend Internal Storage from External Storage Android

images: (http://www.aftvnews.com/wp-content/uploads/2016/12/stick-1-twrp-wipe-menu.png)

Part 1. Install TWRP.
1.1. Software you need: Odin3 https://odindownload.com/
1.2. Driver you need: Samsung USB Driver https://developer.samsung.com/galaxy/others/android-usb-driver-for-windows
1.3. File you need: TWRP;
1.3.1. Open https://twrp.me/Devices and search your devices to get Code Name of Device.
1.3.2. Download TWRP from https://dl.twrp.me/CODENAME
1.4.a. If you want to install SuperSU (Root) after TWRP, Download: SR3-SuperSU-v2.79-SR3-20170114223742.zip and move it to your android internal storage.
1.4.b. If you want to extend internal Storage after Root, Download 'Root Essentials' from Playstore and Download ASPLUGIN.zip: Here

2.1. Turn On Developer Options, OEM Unlock and USB debugging: http://jheb93.blogspot.com/2019/05/how-to-enable-developer-options-usb.html
2.2.a. Restart your smartphone then hold Volume Down + Home while restarting, OR
2.2.b. Turn Off your phone, then Hold Volume Down + Home + Power until Phone is vibrating/On.
2.3. Connect USB cable to PC and Android.
2.4. Press Volume Up to continue to Download Mode.

3.1. Open Odin3.exe
3.2. Click on AP and select TWRP file you've downloaded from 1.3.2
3.3. Click Start and wait until process finished and show "PASS".
3.4. If you want to continue install SuperSU / Extend Storage, Hold Volume Up + Home when PASS is show.

Part 2. Install SuperSU.
1.1. On TWRP Menu, go to Install and select SuperSU file you've downloaded from 1.4.a.
1.1.a. If you want to continue extend storage, uncheck 'reboot after installation is complete', and swipe to confirm Flash.
1.1.b. Go back and select ASPlugin.zip from 1.4.b, check 'reboot after installation is complete' then swipe to confirm Flash.
1.2. After Android rebooted, go to PlayStore and install SuperSU.

Part 3. Extend Internal Storage from External Storage.
1.1. Software you need: Auto-formatting SDCard to Internal and SDCard storage https://forum.xda-developers.com/android/software/auto-formatting-sdcard-to-internal-t3583875
1.2. Extract aftiss_bx.zip to anywhere, and run aftiss.cmd.
1.3. Select mode/storage size in percent you want from external to internal. e.g. 2. 50% : 50%.
1.4. Press 2 and enter.

All Set.

Note: Never disable/uncheck OEM Unlock after root/modif your android.