If you choose RC Cola, you get RC Cola. If picking a soft drink was like the elections, you wouldn’t want to choose RC because you’d still get Pepsi or Coke and you’ll just be throwing away your ability to influence it to be the one with the lower concentration of cyanide.
Fascism is more of an approach than a specific ideology. Its only core value is Strength Through Unity - but to achieve that it needs some populist values to unite the people over - which is how you get different flavors of fascism. The original Fascist Party was using nationalism. Racism is also a popular choice (fascism + racism = Nazism), and it seems like rightist values are more prune to it - but leftist values are not safe either, like we have seen in the USSR which based its fascism around socialism.
Conservatism can be a base for fascism, but like all these other values - it doesn’t have to be fascist. The rule is simple: