Mike42\Escpos\Printer::setEmphasis PHP Method

    public function setEmphasis($on = true)
    {
        self::validateBoolean($on, __FUNCTION__);
        $this->connector->write(self::ESC . "E" . ($on ? chr(1) : chr(0)));
    }

$connector = new FilePrintConnector("php://stdout");
// Add connector for your printer here.
$printer = new Printer($connector);
/* Line spacing */
/*
$printer -> setEmphasis(true);
$printer -> text("Line spacing\n");
$printer -> setEmphasis(false);
foreach(array(16, 32, 64, 128, 255) as $spacing) {
    $printer -> setLineSpacing($spacing);
    $printer -> text("Spacing $spacing: The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog.\n");
}
$printer -> setLineSpacing(); // Back to default
*/
/* Stuff around with left margin */
$printer->setEmphasis(true);
$printer->text("Left margin\n");
$printer->setEmphasis(false);
$printer->text("Default left\n");
foreach (array(1, 2, 4, 8, 16, 32, 64, 128, 256, 512) as $margin) {
    $printer->setPrintLeftMargin($margin);
    $printer->text("left margin {$margin}\n");
}
/* Reset left */
$printer->setPrintLeftMargin(0);
/* Stuff around with page width */
$printer->setEmphasis(true);
$printer->text("Page width\n");
$printer->setEmphasis(false);
$printer->setJustification(Printer::JUSTIFY_RIGHT);
$printer->text("Default width\n");