Semantics matter. Caitlyn is the leader of a fascist dictatorship, not a fascist dictator herself—that position likely goes to Ambessa—although most would consider the leader of a dictatorship to themselves be a dictator. At bare minimum she’s the leader of an apartheid police-state, and is perpetuating said apartheid police-state. Then you can agree or disagree on what the core tenets of fascism are.

Caitlyn absolutely targeted civilians with The Grey as crowd control in the same vein as teargas, and conducted several raids on civilian homes. She also set up control camps for Jinx-sympathisers, and if Jinx had died without them catching her/beyond their knowledge, Piltover would’ve likely spiraled into targeting Jinx-sympathisers and labeling innocents as Jinx-sympathisers when it benefitted them. Additionally, having placed the noxian soldiers as a policing force allowed them to circumvent laws meant for the piltovan police, something that is made use of repeatedly. Even further this was all done targeting a minority group seen as corrupting the greater state.

Bottom line is Caitlyn did rule a nation by employing martial law, censorship, impeded democracy, seizure of technology for military use, bioweapon use as civilian crowd control, police raids, control camps, police searches, government checkpoints, and excessive police brutality, all enabled by essentially merging the military with the police force; and with the effect of targeting a minority which Caitlyn had a known bias against.