I model being happy for others achievements. Because that’s really the best way to feel good. I told my son many times we’re all running our own races. It’s great when someone is doing well in their race. Sometimes we’re doing well in ours, sometimes we’re not. Same for them. When other people do well at things they’re good at, it’s great for them. But it has little to do with us. Comparison is a thief of joy.
I have a lot of experience with this 😊 I have a kid who excels at everything he touches and another who struggles with everything.
Most important is find something they’re good at. Not school related. Anything. Everyone needs wins sometimes and if they don’t come at school, go find them somewhere else

Parents should teach kids to say “what’s your favorite thing about mayv?” Not “I’m in x levels ahead what about you?” This is just basic decency. Bit alas, parents can be jerks

People brag when they are excited or to make themselves feel better. Unless it’s truly malicious bullying, then the response to the friend is:

Congrats, that’s great for you.

End scene.

Tell your kid:

Life is interesting because we all have different spice to add to the pot. Be your own flavor.

There is no sense comparing cinnamon to oregano.

My kid has ASD and dyslexia and anxiety, and it’s rough. One thing that helped was offbeat, non competitive activities, like parkour, where it’s harder to compare. Another thing that helped was finding a good peer group, so camps, etc with “kids like him” so he wasn’t always feeling like the one that was struggling.