In your theme > app/design/frontend/package/theme-name/etc/view.xml Inside <media> node you can define different image sizes:

<images module="Magento_Catalog">
    <image id="product_page_image_medium" type="image">
        <width>300</width>
        <height>300</height>
    </image>
</images>

<script type="text/x-magento-init">
{
    "[data-gallery-role=gallery-placeholder]": {
        "mage/gallery/gallery": {
            "mixins":["magnifier/magnify"],
            "magnifierOpts": <?php /* @escapeNotVerified */ echo $block->getMagnifier(); ?>,
            "data": <?php /* @escapeNotVerified */ echo $block->getGalleryImagesJson(); ?>,
            "options": {
                "maxheight": "700", // Add your value here
           }
        }
    }
}

Thanks

In your theme > app/design/frontend/package/theme-name/etc/view.xml Inside <media> node you can define different image sizes:

<images module="Magento_Catalog">
    <image id="product_page_image_medium" type="image">
        <width>300</width>
        <height>300</height>
    </image>
</images>

Please Change Option Value in

app/design/frontend/Magento/Luma/Magento_Catalog/templates/product/view/gallery.phtml

<script type="text/x-magento-init">
{
    "[data-gallery-role=gallery-placeholder]": {
        "mage/gallery/gallery": {
            "mixins":["magnifier/magnify"],
            "magnifierOpts": <?php /* @escapeNotVerified */ echo $block->getMagnifier(); ?>,
            "data": <?php /* @escapeNotVerified */ echo $block->getGalleryImagesJson(); ?>,
            "options": {
                "maxheight": "700", // Add your value here
           }
        }
    }
}

Thanks

In your theme > app/design/frontend/package/theme-name/etc/view.xml Inside <media> node you can define different image sizes:

<images module="Magento_Catalog">
    <image id="product_page_image_medium" type="image">
        <width>300</width>
        <height>300</height>
    </image>
</images>

Thanks

In your theme > app/design/frontend/package/theme-name/etc/view.xml Inside <media> node you can define different image sizes:

<images module="Magento_Catalog">
    <image id="product_page_image_medium" type="image">
        <width>300</width>
        <height>300</height>
    </image>
</images> 

<script type="text/x-magento-init">
{
    "[data-gallery-role=gallery-placeholder]": {
        "mage/gallery/gallery": {
            "mixins":["magnifier/magnify"],
            "magnifierOpts": <?php /* @escapeNotVerified */ echo $block->getMagnifier(); ?>,
            "data": <?php /* @escapeNotVerified */ echo $block->getGalleryImagesJson(); ?>,
            "options": {
                "maxheight": "700", // Add your value here
           }
        }
    }
}

Thanks