Social media especially Twitter is completely overrun by right wing accounts - but I think most people see through it and it’s having the reverse effect. Hence Labour are going to smash the Tories (who are pandering to the extreme right) in the election.
I think people are going to vote Labour because of their own personal experience of living under the Tories more than anything else. A lot of the criticism of the Tories (and Brexit) over the last 14 years has been theoretical, ideological, or affecting 'someone else.' I think we've finally got to the stage where almost everyone, not just 'benefit scroungers,' young families and the working classes, has suffered a drop in living standards. Even people on low six figure incomes are noticing the problems now. Mortgage prices up, energy prices up, taxes up, and every public service delivering a worse service. I reckon that's got more to do with it than Twitter.
On the main question, I think people have short memories tbh. I remember when the whole political discourse was determined by a handful of right-wing media sources. The Sun and the Star were doing "PC-gone-mad" long before the "woke brigade" was a term. Explicitly homophobic and racist headlines were commonplace.
There's definitely an argument that it makes this more polarized, but let's not pretend that people reading these newspapers back in the day were getting some sort of carefully curated, balanced view of the news.
I think it's made some people more extreme in general, but that's not exclusive to the right wing. Out-and-out conspiracies are definitely more of an issue though, because as bad as the newspapers above are, they do have a certain amount of legal responsibility that doesn't exist for social media.