PHP Parse error when trying to run composer self-update

I'm trying to update composer, however I'm running into the error below.
`PHP Parse error:  syntax error, unexpected 'class'
(T_CLASS), expecting identifier (T_STRING) or varia
ble (T_VARIABLE) or '{' or '$' in /vagrant/apphome/
vendor/drupal/core-composer-scaffold/Plugin.php on line 48`

PHP version : 7.2.24
Composer version: 1.9

Is there a minimum php version that can be used?