Yes, Composer can generally be used. However, it is currently not available natively on the command line via SSH.
It is possible to use it through the "composer.phar" provided by Composer.
First, connect to your web space via SSH. Then navigate to your project directory.
Follow the steps for command-line installation from the Composer website: https://getcomposer.org/download/
After that, the "composer.phar" file will be available in your project directory. You can use this via the PHP command. So if you have previously
composer require symfony/dotenv
entered, you now need to change it to
php composer.phar require symfony/dotenv
If you have a lower or higher PHP version set as standard than your project requires, you can also call the composer.phar with a specific PHP command. For example
php8.2 composer.phar require symfony/dotenv