The short answer
No. Whey is simply milk protein in powder form. It helps if you struggle to reach your daily protein target with food, but it does nothing more than the same amount of protein from a meal. What builds muscle is training plus your total daily protein.
What whey is
Whey is the liquid part of milk, filtered and dried. A 30 g scoop provides about 20 to 25 g of protein. It is a food, not a product that builds muscle on its own.
What the research says
In the 2018 meta-analysis by Morton and colleagues, protein supplements improved muscle gains mainly by raising total protein intake. Above about 1.6 g/kg a day, adding more brought no further benefit.
When it is useful
If you eat little meat, fish, eggs or dairy, struggle to eat enough, or need a quick option after training or on the go. It is practical and often cheap per gram of protein.
The alternatives
Skyr or Greek yoghurt, cottage cheese, a glass of milk, eggs, a tin of tuna: each provides 15 to 25 g of protein. For plant-based diets: pea or soy protein powder, tofu and legumes.
How to choose one
Check the protein content per 100 g (ideally around 75 to 80 g or more) and the ingredient list. Concentrate is enough for most people; isolate contains less lactose if you are sensitive to it.
Put it into practice
About this guide
STARK editorial guide. Examples explain how to use the library and record training; they are not individual coaching.
Training principles: Morton et al. (2018), British Journal of Sports Medicine.
The session examples come from the STARK program catalogue linked above.