2AM is good for character modelling, especially Hoyoverse style or wuwa style, yet his workflow isn't suitable for beginners, because he focuses on reverse engineering the model. However, you can buy his Patreon for 5$ and get access to his model, and you can use it as your portfolio
ChicaArt is good for VTuber character modelling, yet this workflow only works in shading topology.
NatsumoriKatsu is good for anime character modelling; again, anime/vtuber modelling focuses on shading topology.
Shonzo is great for the overall modeling workflow.
And again, what do you mean by 2.5D? Is it like Live2D? Or toon shading?
If you want to go like Live2D, the workflow is the same as ToonBoom, After Effect or Live2D.
If you want to go like ToonShading.
Levi Magony channel is great.
Lacruzo channel is great if you use low poly with cartoony/anime style.
Or you can just search outline effect in blender, because to give outline in the model, has various ways.
Check RoyalSkies channel, it's under 4 minutes tutorial, easy to follow, and always to the point, but lacks information about why and how.
VertexArcade is amazing too
However, I advise you not overuse procedural shading/texture; try using image texture, which means you need to paint or use Substance.