Check composer platform requirements
If you ever need to check what php version do composer packages and their dependencies require, there's a special command just for that.
composer check-platform-reqs
The output should look something like below. Maybe without the failed steps.
ext-dom 20031129 success
ext-fileinfo 7.3.19 success
ext-filter 7.3.19 success
ext-json 1.7.0 success
ext-libxml 7.3.19 success
ext-mbstring 7.3.19 success
ext-openssl 7.3.19 success
ext-pcre 7.3.19 success
ext-Phar 7.3.19 success
ext-SimpleXML 7.3.19 success
ext-tokenizer 7.3.19 success
ext-xml 7.3.19 success
ext-xmlwriter 7.3.19 success
lib-pcre 10.32 success
php 7.3.19 league/commonmark requires php (^7.4 || ^8.0) failed
php 7.3.19 league/config requires php (^7.4 || ^8.0) failed
This is useful when your app fails due to unfulfilled dependency requirements.