Answers for "Root composer.json requires php ^8.0 but your php version (7.4.16) does not satisfy that requirement"

Root composer.json requires php ^7.2.5 but your php version (8.0.6) does not satisfy that requirement.

composer install --ignore-platform-reqs

Root composer.json requires php ^7.2.5 but your php version (8.0.3) does not satisfy that require

It's becouse in your project in composer.json file you have:

"require": {
    "php": ">=7.3",
    .....
},
Try to update this requirement to:

"require": {
    "php": "^7.3|^8.0",
    .....
},