I feel like I used to use a tool called Beyond Compare that presented _many_ different views of a diff (and even supported N-way diffs) back around 2012.
It’s still around and has hardly changed one pixel since 2012!
Yet it still feels fresh and there is no competing product that can challenge them. Most other diff tools lack good merge capabilities and are subpar in multitude of other ways.
P4Merge (https://www.perforce.com/products/helix-core-apps/merge-diff...) is a similarly powerful (and similarly ugly) tool for plain text diffs and three-way merges. It’s free, and though the 500 MB download includes Perforce, you can install P4Merge by itself. Unlike Beyond Compare, though, P4Merge cannot highlight syntax in the compared files.