Not really.
Colonialism is proto-fascism or more correctly fascism is merely colonialism turned on white people by their immediate neighbors instead of an empire an ocean away. All the tactics and horrors of fascism were adopted from colonial practices by European empires in Africa, by American settler colonizers in the Americas, etc. The mass propaganda model was designed based on American advertising psychological studies and practices. The only true innovations were mechanization (use of extensive trains, computer systems for organizing the exterminations, etc), and white people being the victims. Fascism itself arose specifically due to the threat of socialism as a way of combating it by the capitalists.
Monarchism is an unjust, vile, backwards, reactionary system of government and rule. It has presided over colonialism but it also predated it and colonialism has also occurred from nations without monarchies (US is prime example, but France is another, they continued colonialism well into the very end of the 20th century long after they chopped off the heads of their own monarchs and some including myself would argue their neo-colonialism has continued right up until recent events like the formation of AES in the African sahel).
Now I haven’t thought a lot on this particular question or explored it in depth looking for a connection (maybe you can find one if you want to start drawing lines from x through y to then z) but right now I wouldn’t say that there is any kind of direct line from monarchism to fascism per se. Monarchism upholds itself through brutality and injustice yes and is predicated on unjust thinking and supremacy and I suppose one could explore the influence of monarchism and monarchist thinking on the development of colonialism and racism but in truth capitalism and proto-capitalist modes of production are the father of fascism via the development of colonialism.
No need to be rude. Let me attempt to further elucidate on my point.
Colonialism came before fascism was ever coined or uttered much less a movement that’s true but I dispute it being an entirely different animal and insist it’s merely colonialism adapted for specific circumstances of a specific time in Europe. Some people might say just the same that it was “proto-fascism” and our disagreement is not about what came first but whether it is a different animal instead of just a rebranding.
I think the conversation about colonialism as an enduring phenomenon is more important to center the conversation around than allowing certain parties to reframe the conversation and the victim-hood of 20th century European people as particularly special and unique and isolated from these practices when there are so many clear connections openly admitted by the perpetrators themselves.
Don’t ask meaningful questions about history and politics and systems and then get defensive when people give you academic answers that address it and give context and information. Don’t agree? That’s fine.
Now for you I’ll even expand a bit further since you’re so fixated on “proto”. History is not a series of events happening in separate vacuums. It is a series of connected processes going back all the way to the start. Some connections are stronger than others yes, some closer to one another, directly preceding or even being necessary for the development of for example.
Fascism is a loaded word. People bandy it about not to mean a specific phenomenon in Europe in the 20th century from say the 1920s to the mid 1940s centered on Germany and Italy but to mean broadly “oppressive bad political system or act”. Yet that’s not what it was or means. If you’re using it in those loose and inaccurate terms then well there are lot of historical oppressive, repressive, reactionary, and what we might call bad systems including but not limited to monarchy. But in my opinion there’s no direct line between monarchism and the actual historical fascism. Monarchism didn’t directly give rise to it. Arguments about whether it was historically necessary are more complicated, I’ll just say that colonialism was much, much more necessary as was the American example of genocide and settling and for that matter as was capitalism. For that matter the rise of socialism was a necessity because fascism existed and rose to power in opposition to communists and its rule was seen as preferable to the communists by big business and industry and by a variety of reactionary political ideologues and ideologies including but not limited to monarchists.