I'm looking at Neptune Linux, which uses Plasma v5.12.7 with Debian stable. In configuring Desktop Effects, most of the features I'm interested in have been enabled, but several are not. I've noticed Track Mouse and Mouse Click Animation have no effect on Neptune when they are selected. I'm just guessing that the desktop effects are divided into several supporting libraries, and Neptune chose not to bundle certain libraries. Can you identify what supporting package includes those features so I can manually add it? Thanks.

Further research seems to indicate that the issue isn't a missing package. It's likely related to one of the issues that has been periodically reported over many years. If I understand correctly, all of the desktop effects are provided by kwin, and what works or doesn't work is heavily dependent on the compositor and window manager (and the hardware supporting it, although that isn't an issue in my case). The same issue is replicated in Kubuntu (current version), and an older version of Mint KDE.

In all cases, typing "kwin" in the terminal produces a message that "kwin is unable to claim manager selection, another wm running?", and suggests trying to use --replace. I don't know whether that would be a temporary or permanent change, or what else might be affected, so I'm not going to mess with it. Despite kwin apparently not being in control, some kwin effects, like the desktop cube, do work. So go figure.

Unless I stumble across a solution, I'm going to abandon this issue since it isn't worth the time to pursue it.

running "kwin --replace" should shut down the current kwin instance (or whatever other window manager you may be running if not kwin) and start a new instance, preserving any windows you currently have open. Subsequently it should also start printing any (debug) output to that console window, which may provide some useful information.

The set of effects that are available may depend on the capabilities of the graphics card, the drivers being used or the extensions and other libraries you have installed. One thing you can try is go into System Settings -> Desktop Behavior -> Desktop Effects and try enabling some of the effects that you are interested in. If your system doesn't support them, I believe it should pop up a message stating why.