I haven't tried limiting clock speeds to keep the laptop cool, and it seems a bit crazy investment to buy a laptop to try that, but I do have an old MBP with Intel that I can test this with.
You won't see power efficiency and temps comparable to apple silicon on the Intel MBPs, being 14nm, though you can probably get a nice marginal improvement like giving up 10% performance for 20% less power draw. The newer chips from AMD and Intel are comparably efficient to apple silicon with a restrictive power envelope.