The function str_split() is not 'aware' of words. Here is an adaptation of str_split() that is 'word-aware'.

<?php

$array =  str_split_word_aware(
    'In the beginning God created the heaven and the earth. And the earth was without form, and void; and darkness was upon the face of the deep.', 
    32
);

var_dump($array);

/**
  * This function is similar to str_split() but this function keeps words intact; it never splits through a word. 
  *
  * @return array<int, string>
  */
function str_split_word_aware(string $string, int $maxLengthOfLine): array
{
    if ($maxLengthOfLine <= 0) {
        throw new RuntimeException(sprintf('The function %s() must have a max length of line at least greater than one', __FUNCTION__));
    }
    
    $lines = [];
    $words = explode(' ', $string);

    $currentLine = '';
    $lineAccumulator = '';
    foreach ($words as $currentWord) {

        $currentWordWithSpace = sprintf('%s ', $currentWord);
        $lineAccumulator .= $currentWordWithSpace;
        if (strlen($lineAccumulator) < $maxLengthOfLine) {
            $currentLine = $lineAccumulator;
            continue;
        }

        $lines[] = $currentLine;

        // Overwrite the current line and accumulator with the current word
        $currentLine = $currentWordWithSpace;
        $lineAccumulator = $currentWordWithSpace;
    }

    if ($currentLine !== '') {
        $lines[] = $currentLine;
    }

    return $lines;
}

?>

OUTPUT: 

<?php

array(5) {
  [0]=> string(29) "In the beginning God created "
  [1]=> string(30) "the heaven and the earth. And "
  [2]=> string(28) "the earth was without form, "
  [3]=> string(27) "and void; and darkness was "
  [4]=> string(27) "upon the face of the deep. "
}

?>