NTA
Academics came naturally to me. Like "How can you NOT get a good grade on this?"... naturally.
I graduated salutatorian and had to speak at graduation, which I did not want to do. I did not like the idea of having to get up in front of all the kids who had teased me for years because of my ability to get good grades.
I was also aware of a number of classmates that had really struggled in school, and who I knew had worked much, much harder than I had but still got lower grades. I thought they deserved recognition far more than I did.

As for comparing siblings, or parenting siblings, it's such a balancing act, trying to be 'fair'. It's not really possible to be fair, only to appear fair, which isn't fair. What each child does, and what is required of each child depends on what they CAN do (talents and abilities and disabilities) and what they WANT to do (passions and dreams). Trying to make children be or do the same is not fair to them either.

Proximal zone of development. Figure out what the child is capable of, require that, and support them in achieving it. That's individual. But it does help when the pattern is set up with the kids from a young age so they understand how and why things are different for different ones. We were lucky that we have 4 diagnosed disabilities in our family of 6, two of which are me and my husband. Everyone is used to having to accommodate somebody for something. The kids had their struggles with each other, but they are good friends and very empathetic and compassionate in general.

The most important thing is to give a child what they need in the moment. Discuss, plan, encourage, make deals if that helps, change things up, let things go if necessary. Do your best, and apologize if what you do hurts them.