You can use foreignobject for more control and placing rich HTML content over rect or circle
<svg width="250" height="250" xmlns="http://www.w3.org/2000/svg">_x000D_
<rect x="0" y="0" width="250" height="250" fill="aquamarine" />_x000D_
<foreignobject x="0" y="0" width="250" height="250">_x000D_
<body xmlns="http://www.w3.org/1999/xhtml">_x000D_
<div>Here is a long text that runs more than one line and works as a paragraph</div>_x000D_
<br />_x000D_
<div>This is <u>UNDER LINE</u> one</div>_x000D_
<br />_x000D_
<div>This is <b>BOLD</b> one</div>_x000D_
<br />_x000D_
<div>This is <i>Italic</i> one</div>_x000D_
</body>_x000D_
</foreignobject>_x000D_
</svg>
_x000D_