Short answer, no.
Lets say there's a constituency that had the following results in the 2019 election:
Conservative 43% of the vote.
Labour 32%
Lib Dems 11%
Other parties 14%
Conservatives win the seat.
This time, reform take 20% of the conservative vote, and we get
Labour 32%
Conservatives 22%
Reform 20%
Lib Dems 11%
Other parties 14%
Labour vote share hasn't changed, but they've one the seat and their candidate becomes the MP. Repeat that in a load of other constituencies and boom, you have a labour government with a huge majority.
Welcome to "First Past the Post". It's shit. (And I say that as someone who's going to be deeply happy with a labour government.
Labour don't have to increase their vote massively (although it looks like they will come election day). They just need Conservative voters to vote lib dem, or Reform, or even just stay home.
Labour will win, but number of votes will have very little to do with it really. What really matters is how much the Conservative vote splits. And this election, no fucker wants to vote Tory.