Cannot update python in Conda by following Conda documentation

I’m running MacOS Sequoia: 15.6.1

I want to update miniconda python 3.9 to 3.12.

I first updated miniconda and packages via

conda update conda
conda update --all

The current version is conda 25.9.1.

But the current version of python is still 3.9

Python 3.9.25 (main, Nov 3 2025, 22:29:32) [Clang 20.1.8 ] ::
Anaconda, Inc. on darwin

I followed the conda documentation and answer to a previous question

conda create -n py312 python=3.12

but I received the error

Channels:

Platform: osx-arm64
Collecting package metadata (repodata.json): done
Solving environment: failed

PackagesNotFoundError: The following packages are missing from the target environment:

So I backed up and tried a previously suggested step from the conda documentation

conda search python

and received a similar error

Loading channels: done No match found for: python. Search: python

PackagesNotFoundError: The following packages are missing from the
target environment:

I’m stuck. What am I missing here? How do I update to python 3.12 in miniconda?