Size isn’t important, it’s what you do with it that counts
At the 2017 and 2019 elections Labour massively outnumbered the Tories in terms of members but Corbyn still managed to lose both elections and oversaw Labour’s worst election defeat since 1983 so there should be no automaticity that the new party’s membership means an election victory.
I suspect at next year’s election Your Party will win fewer seats than the seats they will cost Labour.
TSE