Virtually all Android devices are capable of running 64-bit software but Google Chrome has never made the jump and is only available in a 32-bit flavour.
This has meant some unnecessary security and performance degradations.
However starting with Chrome 85, phones running Android 10 and higher will automatically receive a 64-bit version.
When compared in a number of Octane 2.0 benchmarks, the 64-bit version got consistently better results than the 32-bit version. It's possible that there have been other optimisations that make Chrome 85 faster than 83 -- the architecture is not necessarily all there is to it.
The benchmark results suggest that there are some enhancements.