Changes

The dimensions of thumbnails for the list of blog posts can be changed in Settings > Media > General. As of 1/30/2017, thumbnails for these posts are 150x200200x150 (confirmed with inspection).

Changing the thumbnail size for images in related posts is possible under Appearance > Widgets > Right Sidebar/Blog Right Sidebar > Yuzo: Related Post(s) > Style > Height & Width image (relative). However, as of now, it is not possible to change the proportions of these images. Currently the dimensions are supposed to be 140x80 (1.75:1 ratio)but are actually 138x78 (confirmed with inspection).  This means that the main thumbnails are squarer than the sidebar thumbnails, which show 133% more content width-wise.