That would be true for 2019 certainly but I'm not sure it's true for every election, the effect of the leader will vary on the circumstances, it'll be a more prominent decision in one election than another
In 2019, you had essentially two cartoon characters as leaders and the election was very much Blur vs Oasis or The Beatles vs The Stones
Next time, I don't think the leadership will be as high a factor, we aren't dealing with cartoon characters, we're dealing with wallpaper salesmen. It's hard to like either of them but on the other hand its hard to see them as hate figures either. (though that won't stop the media trying)
My opinion has been for sometime that the electoral switch has been flicked with the Tories, they will lose, it would take some sort of electoral miracle for them to win. The anyone but the Tories feeling will be the overarching decision making factor in the way the country votes at the next GE, essentially the leaders don't really matter right now, huge numbers of people will be voting Not Tory because the country really does feel the need to give the Conservative Party an absolute shoeing (and quite rightly so)