Invincible at the Start is a Manga/Manhwa/Manhua in (English/Raw) language, Action series, english chapters have been translated and you can read them here. The Summary is
“Ding, the host has opened the invincible field! As long as the host is invincible in the field…!” As a nerd, Chen Changan travels through the fantasy world, facing countless monsters and ghosts from the outside world, Chen Changan decided not to leave his invincible field before becoming immortal. When he is bored, he occasionally raises a few cute and sweet apprentices, and accidentally cultivated them to become leaders in the spiritual world, which turned the world upside down.
Invincible at the Start