hianime is the best site to watch My Isekai Life: I Gained a Second Character Class and Became the Strongest Sage in the World SUB online, or you can even watch Tensei Kenja no Isekai Life: Dai-2 no Shokugyou wo Ete, Sekai Saikyou ni Narimashita DUB in HD quality. You can also find Revoroot anime on hianime website.