<?php
 
$records = [
    [
        'id'         => 2135,
        'first_name' => 'John',
        'last_name'  => 'Doe',
        'owner'      => [
        	[
              	'id'         =>345,
                'first_name' => 'Johnsssss',
                'last_name'  => 'Doe'
            ]
        ]
    ],
    [
        'id'         => 3245,
        'first_name' => 'Sally',
        'last_name'  => 'Smith',
        'owner'      => [
            [
            	'id'         => 345,
            	'first_name' => 'Johnddddd',
            	'last_name' => 'Doe'
            ]
        ]
    ],
    [
        'id' => 5342,
        'first_name' => 'Jane',
        'last_name' => 'Jones',
    ],
    [
        'id' => 5623,
        'first_name' => 'Peter',
        'last_name' => 'Doe',
    ]
];
 
$first_names = array_column($records['owner'], 'id');
print_r($first_names);

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