in order to create custom layout for Magento 1.x cms pages you have to create a custom module:
Module directory / file(s) structure :
app/etc/modules/Home_PageFullwidth.xml
app/code/local/Home/PageFullwidth/etc/config.xml
app/design/frontend/{Theme-Vendor/{Theme-name}/page/home-page.phtml
app/etc/modules/Home_PageFullwidth.xml
<?xml version="1.0"?><config>
<modules>
<Home_PageFullwidth>
<active>true</active>
<codePool>local</codePool>
<depends>
<Mage_Page />
</depends>
</Home_PageFullwidth>
</modules>
app/code/local/Home/PageFullwidth/etc/config.xml
<?xml version="1.0"?>
<config>
<modules>
<Home_PageFullwidth>
<version>0.1.0</version>
</Home_PageFullwidth>
</modules>
<global>
<page>
<layouts>
<PageFullwidth translate="label">
<label>1Column-fullWidth</label>
<template>page/home-page.phtml</template>
<layout_handle>homepage_fullwidth</layout_handle>
</PageFullwidth>
</layouts>
</page>
</global>
</config>
And finally your template file page/home-page.phtml:
<!DOCTYPE html>
<html lang="<?php echo $this->getLang() ?>">
<head>
<?php echo $this->getChildHtml('head') ?>
</head>
<body<?php echo $this->getBodyClass()?' class="'.$this->getBodyClass().'"':'' ?>>
<?php echo $this->getChildHtml('after_body_start') ?>
<div class="wrapper">
<?php echo $this->getChildHtml('global_notices') ?>
<div class="page">
<?php echo $this->getChildHtml('custom_notice') ?>
<?php echo $this->getChildHtml('header') ?>
<?php echo $this->getChildHtml('topContainer') ?>
<div class="main-container col1-layout">
<div class="main">
<div class="col-main">
<?php echo $this->getChildHtml('global_messages') ?>
<?php echo $this->getChildHtml('content') ?>
</div>
</div>
</div>
<?php echo $this->getChildHtml('footer') ?>
<?php echo $this->getChildHtml('global_cookie_notice') ?>
<?php echo $this->getChildHtml('before_body_end') ?>
</div>
</div>
<?php echo $this->getAbsoluteFooter() ?>
</body>
</html>