Honestly, it depends on what you take them for. Some people assume a pre-workout and think that they are getting bigger, stronger or faster. Probably not, but it certainly can help you destroy an important training. And if you crush many workouts over time, it can definitely help you get bigger, stronger, and faster! Remember that the main purpose of pre-workouts is not directly building muscle or improving your physique give you the energy, stamina and focus to perform the exercises that can help you achieve both goals.
There are numerous studies showing that most of the individual ingredients in today's most popular pre-workouts bring some strength, stamina or muscle growth. However, the training history and training of these subjects can be drastically different from yours.
Short answer: Yes, a pre-workout can help you have a better workout. But the truth is that it is only one factor of many. Make your workout right. Build up your nutritional basis. Optimize your rest with plenty of sleep. And then use additions to destroy the last 5 percent of the project!