how to increase the size of h1 in html code example

Example 1: html h1 left align

<h1 style="text-align:center">Titulo 1</h1>
<h2 style="text-align:left">Titulo 2</h2>
<h3 style="text-align:right">Titulo 3</h3>
<h4 style="text-align:justify">Titulo 4</h4>
<p>...</p>

Example 2: css h sizes

h1  =>    32px    (2em)
h2  =>    24px  (1.5em)
h3  =>  20.8px  (1.3em)
h4  =>    16px    (1em)
h5  =>  12.8px  (0.8em)
h6  =>  11.2px  (0.7em)