Possibly. I think it is unrealistic to say every single Reform vote would go to the Tories if there was some sort of pact. And even then, it would likely be in recount territory for both of those elections last night. But I'm being a bit pedantic. Even if the Tories just held on to what were once massive majorities that would indicate a large Labour majority at the GE. I am keeping an eye on if Reform gives way to the Tories, but it doesn't seem like they will. They exist for a reason, because they don't think the Tories are being right wing enough, and if the Tories try to move more to the right wing, they will alienate their soft right support. This is their problem. The centre/left are voting tactically regardless so Labour so far doesn't have this issue. There is no left wing Reform party (and no, Corbyn isn't creating one).
Labour have more policies than they get credit for, although I hardly see them as offering a transformative image of Britain. Nevertheless they are trouncing the Tories in the polls and that is now backed up by local council elections and several by-elections. They are also, interestingly, fighting back against the SNP. I have no doubt Labour would win the next GE just by being boring men in suits who sound a bit competent. It is literally happening as we speak. Campaign is still a long way away, let's see what their manifesto ends up looking like.