Pull portions of data from a db field and create multiple variables

From your description

option1=value1
option2=value2
option3=value3

isn't an array, but a text field with line breaks. You should do

$myarray=explode("\n",$textfield);

to get a proper array.

From then on, your attempted solution seems to rely in converting that array into a query string you will pass with a GET request to another page. For that matter, you can implode the array using & as the glue.

However you also said that you need to convert array items into variables. For that purpose, you can create a new array in the form

$assocarray=[];
foreach($myarray as $item) {
  $keyvalue=explode('=',$item);
  $assocarray[$keyvalue[0]]=$keyvalue[1];
}

which will result in $assocarray being

Array [
    'option1' => value1,
    'option2' => value2,
    'option3' => value3,
];

So you could perform

extract($assocarray);

to get 3 variables called $option1, $option2 and $option3 in the global namespace.

Edit: I see that, for some reason, you have nested arrays. Something like

$myarray = Array [
                  Array [ 
                     "access_optin=2", 
                     "", 
                     ""
                  ],
                  Array [
                     "show_bio=1",  
                     "show_url=1", 
                     "show_picture=1", 
                     "show_organization=1", 
                     "access_optin=2", 
                     "access_jobtitle=0",  
                     "access_email=0"
                  ]
            ];

and the iteration should be

$assocarray=[];
foreach($myarray as $subarray) {
    foreach($subarray as $item) {
        $keyvalue=explode('=',$item);
        if(count($keyvalue)==2) $assocarray[$keyvalue[0]]=$keyvalue[1];
    }
}

Note that I'm validating the size of the $keyvalue array, because some not every value will have the name=value pattern.

Second Edit:

Since each $subarray represents a different user, you need to store the parsed key/value pair in a subarray too.

$assocarray=[];
foreach($myarray as $user => $subarray) {
    foreach($subarray as $item) {
        $keyvalue=explode('=',$item);
        if(count($keyvalue)==2) $assocarray[$user][$keyvalue[0]]=$keyvalue[1];
    }
}

This assumes your $user matches the user_id you need to set. Otherwise, you'll have to go a bit backwards to where you give form to the $myarray variable. I'm afraid you'll need to, because your example starts with zero and I bet your user_id doesn't.