Generally, if you load font as preload, it will load first and it will help to increase site speed.
So If you want to add custom font as preload, you need to perform settings as shown below:
The first step is to set your font .woff or .woff2 file in your theme web/fonts folder.
Then after you need to set that font in between head like below in default.xml layout file.
<?xml version="1.0"?> <!-- /** * Copyright © Magento, Inc. All rights reserved. * See COPYING.txt for license details. */ --> <page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd"> <head> <font src="fonts/custom-font.woff2"/> </head> </page>

