Take ImageMagick 7 changes into account (problems with COMPOSITE_ADD, COMPOSITE_MINUS, COMPOSITE_SUBTRACT)

ImageMagick version string can be different on different platforms.
versionString = "ImageMagick 7.1.1-43 Q16-HDRI x86_64 22550 https://imagemagick.org";
In this case we need only the "major" part of the version, but the "-43" is still part of the version string.

  public static function getVersion(): ?string {
    $version = \Imagick::getVersion();

    $matches = [];
    preg_match(
      '/^ImageMagick\s+(?P<version>\S+)/ui',
      $version['versionString'],
      $matches,
    );

    return $matches['version'] ?? NULL;
  }

Without version checking:

    if (defined('\Imagick::COMPOSITE_ADD')) {
      $composites[\Imagick::COMPOSITE_ADD] = 'Add';
    }

    if (defined('\Imagick::COMPOSITE_MINUS')) {
      $composites[\Imagick::COMPOSITE_MINUS] = 'Minus';
    }

    if (defined('\Imagick::COMPOSITE_SUBTRACT')) {
      $composites[\Imagick::COMPOSITE_SUBTRACT] = 'Subtract';
    }

Position of the options still not the same as the original.

Labels are not translatable, but that is another issue.

Function \version_compare() has third paramater to make it easier to get a boolean result.

Function \Drupal\imagick\ImagickConst::composites() is used by
\Drupal\imagick\Plugin\ImageEffect\CompositeImageEffect::buildConfigurationForm().

An image effect has to be image_toolkit independent.

Options 2=>Add, 36=>minus and 52=>Subtract are removed even when the active image_toolkit is GD.

Existing image styles – saved with ImageMagick 6.x – can store references to composite options that are not exists in ImageMagick 7.x.

In function \Drupal\imagick\Plugin\ImageToolkit\Operation\imagick\Composite::process() there is \Imagick::compositeImage() call with the stored value, without checking it if it valid or not.
I don't know how the \Imagick::compositeImage() will react in that case.

I think \Drupal\imagick\Plugin\ImageToolkit\Operation\imagick\Composite::validateArguments() should be implemented. Or just transform an unknown value to the closest valid value.