The minimum requirements for Drupal is listed on their official page here:
The table below was taken from their website as of 22 June 2022 and lists all the supported and recommended version of PHP for Drupal 7.
|PHP version||Supported by Drupal||Recommended for Drupal 7?|
|5.3 / 5.4 / 5.5||Yes||No|
|7.4||Yes, as of Drupal 7.71||Yes|
|8.0||Yes, as of Drupal 7.79||See official Drupal link|
|8.1||No; see official Drupal link|