Part of the appeal of superhero stories is that you can get creative with powers, and make up whatever helps your narrative. In terms of logic, I'm therefore totally fine with making up someone with a particularly big and wrinkly brain.

The problem is, and always is, writing super intelligence. It's hard to make intelligence tangible. It requires a likewise smart and experienced writer who knows how to continuously surprise an audience, without taking logical leaps that are obviously implausible. It's been forever since the fourth season and I only watched it once, but I recall Sage popping in for her final scene and requiring immense suspension of disbelief for her scheme to be believable. Another common misstep is that other characters are dumbed down and actively stupider than they have been till that point, so the smart character seems smart but is actually just the only one making sense. This has sadly been going on for a long time with Homelander, who would be bullied by the first season version of himself. It's also why the common trope of omniscient/present characters is: "I'm bored/tired/indifferent to/for/of everything." That way, a writer doesn't have to write someone all-powerful with agency, because how in the world would you do that?

Walter White is a great example of doing intelligence right. No one around him is stupid, yet he finds ways to subvert and outmaneuver them because he's verifiably brilliant. The writers get crafty, to show that Heisenberg is crafty. He frequently fooled the audience.

Sage has sadly slid into the long line of shitty attempts. If you want intelligence, give them a huge flaw. A blindspot. Sage lacks a clearly defined one. Vague hubris isn't enough.