Ezekiel 1:15-16
Now as I looked at the living creatures, behold, a wheel was on the earth beside each living creature with its four faces. The appearance of the wheels and their workings was like the color of beryl, and all four had the same likeness. The appearance of their workings was, as it were, a wheel in the middle of a wheel.

What is a wheel?
You might say an object on a car or truck and available in a variety of styles and sizes. Wheels are on bicycles and motorcycles. There is a spinning wheel, a steering wheel, and a potter’s wheel, which all look different.
The dictionary gives these definitions: a circular frame of hard material that may be solid, partly solid, or spoked and that is capable of turning on an axle. A chiefly medieval instrument of torture designed for mutilating a victim (as by stretching or disjointing). Something (such as a round, flat cheese) resembling a wheel in shape. A recurring course, development, or action: a cycle. A curving or circular movement

Again, language plays a huge part in meaning.
If you envision a wheel in the middle of a wheel you could think of something like a gyroscope or a large wheel with a smaller inside or any number of things.
Toss in the living creatures and it’s really difficult to imagine.
Perhaps it was just as difficult for Ezekiel to describe.

Everyone deals with a wheel within a wheel every day.
The orbit of the earth is a wheel – a cycle inside other cycles. The solar system is a wheel in the Milky Way galaxy, which is a wheel in the universe.
Many of these cycles are predictable.
We know the seasons of the year, the phases of the moon, the return of comets, and the times and paths of solar and lunar eclipses.

The Feasts of the Lord are a wheel, a constant cycle.
The Old Testament is a wheel.
The New Testament is a wheel. Each is connected to the other and Jesus is the commonality.
Have you ever read something in the OT only to think of something in the NT? As you read it you get directed back to the OT. A wheel within a wheel. A cycle!

Jesus is like a wheel or a circle. He is the same yesterday, today, and forever. He is without beginning and without end. He sees Abraham and David at the same time He sees you. He knows 4000 B.C. and He knows 2025 A.D.
Christ is the wheel within the wheel.