That was a useful extension.
The BreakPost extension that comes with BE is enabled by default and might do the trick, To use it, make sure "Only show description of posts" in settings is unchecked, then add marker [more] in post body wherever you would like the post truncated
for list views, In post lists you will see shortened version of post along with any images that are present before the [more] breakpoint in post body.
If you want to use the "Only show description of posts" option then this will require some coding. here are a couple of examples:
Both examples are a little old now and were intended for previous versions of BE(the newer razor themes are different), but principles are still the same.
The advantage of this approach is that it will give you more control over image size and placement in previews.