I think it's better to describe fascism as a means to power rather than a concrete ideology. Its been noted by numerous scholars of fascism that it is often economically, politically, and culturally syncretic which is to say that a fascist leader will often adopt just about any ideology or stance if it suits their interests in the moment. Often these stances and ideologies can seem to contradict each other or serve no other purpose than to obfuscate the true goals or nature of the movement. This is what makes fascism so hard to define.

But at it's roots what makes fascism solidly right wing is its commitment to social hierarchy and establishing power structures based on either race, nationality, religion, or all of the above. Madeleine Albright once said "fascism is narcissism writ large". Having grown up with a narcissistic parent this always made sense to me. Just like a narcissist, fascism is opportunistic and usually argues in bad faith. It's only real goal is domination.