When comparing a CPUs, you have to focus on the specific CPU models, because there are different processor families, types, generations etc.
The basic differences between 12th generation i3, i5 and i7 processors are:
|Core i3 12100||3.30 GHz||4.30 GHz||4||8||12 MB|
|Core i5 12400||2.50 GHz||4.40 GHz||6||12||18 MB|
|Core i7 12700||1.60 GHz|
|4.90 GHz||8 + 4||20||25 MB|
Processors Intel Core i5 and i7 can perform better than Intel Core i3, because they have more cores and threads, higher smart cache memory and higher turbo boost frequency. But even though the differences between them, Intel Core i3 12th generation processors can provide a solid performance. Intel Core i5 and i7 are better when using a CPU intensive software.
To get more details about processor performance, you have to check a benchmark comparison, where you can find more characteristics, so you can see what is an approximate difference between CPU models. The fact that Intel Core i7 has 3x more cores than Intel Core i3, doesn't automatically mean that it is 3x faster.