I find Stillwell's writings to be exceptionally clear and accessible, and I recommend them.

It will be interesting to see if Tao's writings are as clear, though possibly he is targetting a different audience.

From Book Details;

a brief tour of six core ideas—numbers, algebra, geometry, probability, analysis, and dynamics—that capture the beauty and power of mathematical thinking for everyone.

In Six Math Essentials, the renowned mathematician and Fields Medalist Terence Tao introduces readers to six central concepts that have guided mathematicians from antiquity to the frontiers of what we know today and now help us make sense of our complex world. This slim, elegant volume explores

numbers as the gateway to quantitative thinking;

algebra as the gateway to abstraction;

geometry as a way to calculate beyond what we can see;

probability as a tool to navigate uncertainty with rigorous thinking;

analysis as a means to tame the very large or the very small; and

dynamics as the mathematics of change.

Six Math Essentials—Tao’s first popular math book

Terence Tao's comment :- This book is for a general audience, without necessarily having a college-level math education. It is aimed more at adults than at children, but some children with an interest in mathematics may be able to get something out of it.

It is just 160 pages so must be information dense with no fluff. I am sold !

PS: Another book in the same (but easier) vein would be Ian Stewart's classic Concepts of Modern Mathematics - https://store.doverpublications.com/products/9780486284248