filesystems.php

<?php

return [
    // ...
    
    'disks' => [
        's3-bucket-1' => [
            'driver' => 's3',
            'key' => 'your-key',
            'secret' => 'your-secret',
            'region' => 'your-region',
            'bucket' => 'your-bucket',    
        ],
        
        's3-bucket-2' => [
            'driver' => 's3',
            'key' => 'your-key',
            'secret' => 'your-secret',
            'region' => 'your-region',
            'bucket' => 'your-bucket-2',
        ]
    ]
];

User.php

<?php

class UserController
{
    Storage::disk('s3-bucket-1')->put('file.txt', '...');
}