Maybe the new efficiency cores improve battery life over the 11th gen Intel CPUs but they're still far from the battery life of AMD or Apple silicon CPUs
For sure.
I believe Intel 12th gen is not properly tweaked yet, currently the benchmarks show that the battery performance is worse with 12th gen than 12th gen. But if you 'limit' the chip and force the usage of the efficiency cores then you should be able to beat 11th gen.
Don't forget 12th gen Intel CPUs have a lot more cores than 11th gen Intel CPUs. That's where the significant benchmark improvements are coming from. Unfortunately though, these often don't reflect the real world use case. Having more cores isn't going to improve the day-to-day performance very much. The new efficiency cores probably improve battery life though