The aimed-for outcome of the protectionist could be said to be the shielding of domestic markets from competition with an "unfair" advantage. For example, an emerging economy might have non-existent workers' rights enabling lower production cost.
However, discussions surrounding naive protectionist policies typically descend into "define a biscuit" type arguments. In short: the difficulty in defining the boundaries of tariffs quickly turns arguments to farce.
But there must be other, better ways to achieve the desired outcome. I have read that in the early 2000s Germany "protected" its intra-EU car sales by ensuring EU emissions regulations were closely aligned with the emissions of their own diesel engine technology making market entry by (for example) American cars with big petrol engines more difficult. Whether this is apochryphal or not, the point remains.
Do free-trade economies typically endeavour to protect themselves in ANY way, or does "free mean free" in the minds of these legislatures?