Is flexing abs the way to proper posture?

[R@m@]

I always tought good posture was standing as straight as possible but some people claim you should flex your abs like in a crunch altought that doesnt make one stand as tall as possible

 

[halloweed]

Flexing my abs makes me taller ngl

I always tought good posture was standing as straight as possible but some people claim you should flex your abs like in a crunch altought that doesnt make one stand as tall as possible