It is require to update iOS?

Hello ~ No….but it is recommended to protect your information and to use new features.

Update your iPhone, iPad, or iPod touch - Apple Support

~Katana-San~

Do you want to have the most up to date security to protect your personal info? If yes, you would want to apply the most recent security updates in the newer version of iOS.

If you are not interested in having the most up to date security to protect your data, then don't update.