Elias here with Shopify Support. Thank you for reaching out.
I understand you're looking to reduce the size of the product thumbnails for the recommended products on the mobile version of your Debut theme. Though I'm unable to confirm how much further the thumbnail sizes can be reduced. However, if your store is subscribed to a plan, I can send a customization to our Theme Support and they can help explore potential options. I've located your shop and I've sent an authentication email to the registered email address we have on file. Please check your inbox/spam/junk folder and send me a reply. That way, I can authenticate your account and forward this request to our Theme Support team.
That's a great question! Providence is a third-party theme, made and supported by Skup - You can submit a support request with them right over here.
You can also get support with third-party themes from Shopify Experts. Experts are experienced in working with third-party themes or custom coding, they'll be able to assist you with the alignment of images on your Providence theme.