Physicists poke their noses into everything, from the smallest to the largest.
The diameter of a proton is about 0.000 000 000 000 0016 m.
Proxima Centauri, the nearest star to Earth, is 40,208,000,000,000,000 m away.
Obviously, when it comes to units, one size does not fit all. This is why the SI system provides for prefixes so that units of different sizes can be formed.
Base vs Derived Units
Why’s a Meter a Meter (SciShow)
The Kilogram has Changed. Here’s Why (Verge Science)
The Mars Climate Orbiter Incident