If they keep everything the same, everything being equal as economists say, smaller geometry (more room to breathe, able to run with ever lower voltage) should reduce heat signature, but unfortunately vendors usually can't help stuffing more stuff, more features, more transistors onto the new design, which negate the smaller geometry advantage. There will probably be some plus thermal advantage but don't expect a huge improvement, judging from history.
With laptops/desktops, like cars, you make a choice whether you want some nimble, quick response sporty thing vs nice roomy comfy SUV. There is no magic.
Now some laptops make extra effort to make it quiet and long battery lasting between charges, in exchange for performance, i.e. Apple. Linus Tech says so in one of his videos.
From this techie's perspective, if programmers take the time to hand-optimize their codes, Apps can run very well wo a lot of horsepower, but nobody does that, it takes too long to hand-code in Assembly (machine language, FAST!) The economic of it all proper programmers to use reusable and human-maneageble high level codes.