This is a male base mesh that is fully rigged animated using mixamo animations.

The rig uses just weights and bones, which makes it easier to edit and manipulate, the base mesh comes from my own internal need to have a good reference base for my painting and illustration process, I bought several different base meshes over time and non fully reacted in the way I desired, specially on the shoulder areas, wich are notoriously hard to rig and weight (as I found first hand while I did the rig and skinning).
It's then designed with that aim, so the shapes and shadows they produce are well shown for a painter to extract information from them to use as a custom light reference for the painting process.
I hope it helps you in yours, I will continue to update the deformation systems it has, this is only version 1_1, it works just fine, but I Im very interested on making as good a reference as I can, the next step is adding some face controls and expressions so it can also used as general portrait reference, as well as some repelling systems so when some parts of the mesh come too close to each other they move apart, this is a system that I envision will work well for some extreme compression of the legs, this 2 updates will be free after you bought this version.

This is what come in the package sort of speak:

1. The mesh, fully rigged IK and FK, snappers for both modes are included, and switchers to change from FK to IK,
2. CHATGPT tools: Im not a coder but managed use ChatGPT to create several tools to ease the use of the rigg, a simple bone collection UI so you can have just the ones you use most, a IK to FK snapper tool, (because of dependency API limitations IK will never fully follow FK to the letter using this but it can still transfer most of the pose from FK to IK and then the user can make manual changes, if after removing the snap you find the IK bones are acting a bit funny is because of this dependency graph issue, just enter edit mode on the rig one and exit this clears the dependencies, and the IK should just work fine) and a small utility that syncs the time line start and end of the current action, there is also a tool to store custom poses, if you see 3 arrows next to some properties of the ui the first down arrow collapses that property so it unclutters spaces the next 2 move the property up and down,  all the tools are on n-Panel.
3. Materials are assigned to main visual muscle groups so you can make sense of the flow of them, but they can be turned off with a geometry nodes material override so you can just focus on the shadows and lighting.
4. Mixamo animation, it has a simple walk, run, attack and acrobatic capoeira kick, they were taken from Mixamo, they were cleaned to some extent but they are not meant to be the core of the usability of the character, they are there to be used as a starting point for a reference pose, then edited by the user once the pose is frozen.

This is a you-tube video that shows the rig in action so you can gauge its functionality:

This 2 show the deformation at work alone:

This is mostly the technical parts of how it works:

Thank for your time, Cheers!!