If you enabled Magic Shader but your character still looks like the default model, work through these checks in order.
Check that the pack is actually active
1. Open the menu where you enabled the pack: Video Settings > Shader Packs, or Options > Resource Packs.
2. Confirm Magic Shader is selected and not just sitting in the available list.
3. If you use a shader loader, remember that only one shader pack can be active at a time. Selecting a different pack turns Magic Shader off.
4. Make sure you are looking in third person (F5). Your own model is not visible from first person.
Rule out conflicts and reload
1. Resource pack users: other packs placed above Magic Shader in the Selected list can override it. Move Magic Shader to the top and click Done.
2. Temporarily disable other packs that change player skins or models. Then check whether your model appears.
3. Press F3 + T in-game to reload resources after making changes.
4. If nothing changes, close the game completely and relaunch it so the shader files load fresh.
5. Check the pack file in its folder. It should sit directly in the folder, not inside a second folder created when you unzipped it.
After each fix, load a world, press F5, and look at your character. That way you can tell which step solved the problem.