Symfony 5.4.9 Composer detected issues in your platform:

I am totally new to Symfony. After I installed Symfony on my local ddev machine, I get this error

Fatal error: Composer detected issues in your platform: Your Composer dependencies require a PHP version ">= 8.1.0". You are running 7.4.29. in /var/www/html/symfony/vendor/composer/platform_check.php on line 24

I tried to composer install --ignore-platform-reqs as well, and soon as I run it, I get this error message

Parse error: syntax error, unexpected '|', expecting variable (T_VARIABLE) in /var/www/html/symfony/vendor/psr/log/src/LoggerInterface.php on line 30

My php version is

❯ php -v
PHP 8.1.6 (cli) (built: May 12 2022 23:44:22) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.1.6, Copyright (c) Zend Technologies
    with Zend OPcache v8.1.6, Copyright (c), by Zend Technologies

Compose.json

    "type": "project",
    "license": "proprietary",
    "minimum-stability": "stable",
    "prefer-stable": true,
    "require": {
        "php": ">=7.2.5",
        "ext-ctype": "*",
        "ext-iconv": "*",
        "symfony/console": "*",
        "symfony/dotenv": "*",
        "symfony/flex": "^1.17|^2",
        "symfony/framework-bundle": "*",
        "symfony/runtime": "*",
        "symfony/yaml": "*"
    },
    "require-dev": {
    },
    "config": {

Thanks for help

Answer

Edit these 2 things in your composer.json to solve your problem :

 "require": {
        "php": ">=8.1",
}

And

"config": {
        "platform": {
            "php": "8.1.6"
        },
    },