Within the sidebar, the cart items are being shown - each with their corresponding product image. This playbook shows you how to customize things.
Create a file view/frontend/layout/loki_checkout.xml and add the following:
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:View/Layout:etc/page_configuration.xsd">
<body>
<referenceBlock name="loki-checkout.sidebar.items.item">
<arguments>
<argument name="size" xsi:type="number">80</argument>
</arguments>
</referenceBlock>
</body>
</page>
This changes the size, which correspondingly changes the width and height.
If you want to change the width and height independent of each other, use the following:
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:View/Layout:etc/page_configuration.xsd">
<body>
<referenceBlock name="loki-checkout.sidebar.items.item">
<arguments>
<argument name="width" xsi:type="number">40</argument>
<argument name="height" xsi:type="number">70</argument>
</arguments>
</referenceBlock>
</body>
</page>