If You are using lower version of Android, Like Android 5 or 6. And if you want to Run Termux on it. In this page you will get your solution how to do that.
https://archive.org/download/termux-repositories-legacy/termux-v0.79-offline-bootstraps.apk
termux-setup-storage && cd ../usr/etc/apt/sources.list.d && rm -rf * && cd ~ && cd ../usr/etc/apt/ && rm -f sources.list && echo "deb http://packages.termux.dev/apt/termux-main-21 stable main" > sources.list && cd ~