Paste this CSS code into Appearance>Customize>Additional CSS. The first one is for the Home page and the second one is for the Category page. Adjust the height greater or lesser to your taste. This will reduce the height of the "white space".
.product-small .woocommerce-loop-product__title {
height: 5px;
}
.product-small .product-box .box-text a {
height: 65px;
}
As for the image height, you'd need to create a child theme and edit theme files. But I think you may be able to increase the whole image size (height and width) in the settings somewhere. **I don't have this theme installed, so I can't be sure. I tried doing it via CSS, but acts more like a zoom effect, which is terrible. Anyway, in my opinion, the image size is fine the way it is.
**I figured out the CSS above from the Davinci Woo Demo.
https://woo-newdavinci.alidropship.com/