PHP version issue when trying to update core

I seem to have resolved this by following these steps:
In composer.json I added this
"platform":{
"php":"8.1.25"
}
below - "sort-packages": true,

That solved the PHP version requirement but running composer "drupal/core-*" --with-all-dependencies said there was nothing to install

Then I ran:
composer require drupal/core-recommended:10.1.6 drupal/core-composer-scaffold:10.1.6 drupal/core-project-message:10.1.6 --update-with-all-dependencies

This updated the site to 10.1.6

- drupal/core 10.1.5 requires php >=8.1.0 -> your php version (8.0.30) does not satisfy that requirement.

This means that when you were running Composer you were using PHP 8.0.30. It is possible to have different versions of PHP on the command line and in the web server. What is the output of php -v?