How can I change the default product images sizes on Magento ver. 2.3.5-p1

Magento 2.3.5 uses the file called view.xml which is maintained at the theme level of the application.

So for example, if you are using the default theme luma you should find the view.xml under vendor/magento/theme-frontend-luma/etc/view.xml

In this file, you would see <images/> node inside the <media> node.

public_html/cheapglasses123.com/vendor/magento/theme-frontend-luma/etc/view.xml

The dimension of the images is maintained here under the <image/> node.

The id attribute value of the <image/> node is referenced in the codebase.

For example:

<image id=”product_page_image_large” type=”image”/>
<image id=”product_page_image_medium” type=”image”>
<width>700</width>
<height>700</height>
</image>

<image id=”product_page_main_image” type=”image”>
<width>700</width>
<height>560</height>
</image>
<image id=”product_page_main_image_default” type=”image”>
<width>700</width>
<height>560</height>
</image>

This will cause the `fotorama__stage` to be smaller – it adjusts based on the image size.