The supporting character's harem is very normal - Chapter 7: F rank talent…

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

The Fake Life of a Villainess: Reincarnated as a villainous noblewoman, you become an experience bag for the protagonist on their journey. You are the target of the maid’s revenge, your half-sister takes away everything that belongs to you, and the grand princess who cared for you for many years finally loses hope and abandons you. The Real Life of a Villainess: You clean up the mess left behind by the protagonist when they disappear. And in their place, you teach her that as a maid, she shouldn’t always be thinking about…

Heath transmigrated to an alternate dimension and awakened the [God-like Extraction System]. With the help of the system, he steadily walked the path of the Witcher to become a god.

Eight hundred years ago, Xie Lian was the Crown Prince of the Xian Le kingdom. He was beloved by his citizens and was considered the darling of the world. He ascended to the Heavens at a young age; however, due to unfortunate circumstances, was quickly banished back to the mortal realm. Years later, he ascends again–only to be banished again a few minutes after his ascension.

Now, eight hundred years later, Xie Lian ascends to the Heavens for the third time as the laughing stock among all three realms. On his first task as a god thrice ascended, he meets a mysterious demon who rules the ghosts and terrifies the Heavens, yet, unbeknownst to Xie Lian, this demon king has been paying attention to him for a very, very long time.

- Description from Novelupdates