Not substantial enough changes unless you’re capable of overthrowing the state. Direct action works best when the state is mostly uninterested in what you’re doing, it’s significantly harder if the state is actively opposed to what you’re doing.

Voting isn’t about solving everything, it’s about making it slightly easier to do direct action. Participation in bourgeois elections is important precisely because it’s never going to get rid of capitalism. It’s the one method of slightly influencing the systems used to opress and undermine working class struggles. You aren’t going to fundamentally change anything by voting, but elections influence how openly and strongly the state opposes direct action.

You don’t throw away a tool just because it doesn’t have much impact, you just use it where it can be slightly helpful.