mm ... I'm not sure what you mean
Do you want to learn how to make mesh, recolors or mods?
if I understood wrong ok but for me:
There will not be a tutorial that tells you step by step what you should do if that is what you are looking for
you also have to experiment with yourself and look for the best possible combination
it requires practice, it requires reviewing a lot n-n
there is more information about recolors, basic things but not so much with the meshes or mods (which change the game in a great sense)
that's why there's the question section in creator help because when you get stuck they try to find the best possible solution, or tell you what's wrong or give you clues
sometimes there is no tutorial of a specific creation
because you need to create it yourself or look for more of that topic
blender takes you to many possibilities in mesh creation
that is, the most common is to use these tools: photoshop, gimp, paint.net (recolors, use of uv image to paint it)
---- If you want to perfect yourself in this field there are many tutorials that are not sims but are useful to create for example: shadows for clothes, brushes for hair ... anyway
Basically, that's what the game is about, right?
Now if your question is which parts make up a object mesh you can get it here:
sims4studio.com/thread/377/components-ea-object--- Blender (creation of meshes) but not any version there, it tells you in the tutorials section
with blender you can: create objects like bears, posters ... in short
but you have to look for tutorials that are not from the sims because basically that's what the game is about
--UV map (uv templates --- template)
for hair it is usual to use 3dmax
for clothes---marvelous designer
--- Mods (script and no script) xml, python (script) in this field is quite common to ask another person who knows more
--- sliders (sliders tutorials are available elsewhere)
anyway, other people can give you their opinion