Yes, you have to choose a weight-based shipping pricing model OR a money-based pricing model, a combination of both is not possible by default.
There are modules for this, but as I've noticed, they usually don't work reliably. Be careful about spending money on it right away.
The weight-based shipping pricing model is a powerful tool. Of course, you have to keep your items (weights) up to date and maintain them. But this makes it possible to present a wide range of shipping solutions.
You don't have to use the real item weight for this.
We have e.g. 0.0001kg for most items plus then the correct weight of 1kg for other (heavy or bulky) items.