I want an advanced text editor that have many functions and good for editing text files. Can you suggest me it?
vim in termux is not your solution, is it?
There is Acode editor - Android code editor | F-Droid - Free and Open Source Android App Repository and Karbon | F-Droid - Free and Open Source Android App Repository or even Emacs | F-Droid - Free and Open Source Android App Repository but going through a terminal as you would on Linux remains the best option as @Jens said. I also recommend using Termux | F-Droid - Free and Open Source Android App Repository and my favorite is https://helix-editor.com 