What intel desktop processor can be match to iphone 8's?

What intel desktop processor can be match to iphone 8's? - 1

It overheats if stressed, and in full performance ranks #261 as an estimated placement
https://www.notebookcheck.net/...986.0.html
Approximates laptop Intel Core i3-7100U
That is impressive for a smartphone.
https://www.cpubenchmark.net/...u_list.php
Scoring 3650 as estimated
Pentium G3470 @ 3.60GHz 3702
Pentium G4500 @ 3.50GHz 3794
In Intel 1151 package,
https://pcpartpicker.com/products/cpu/#k=30&sort=price&page=1
Intel Pentium G4400 3.3GHz2core 54W $49.77 score 3590
Intel Pentium G4500 3.5GHz 2 core 51W $71.35 score 3794
Intel Pentium G4600 3.6GHz 2 core 51W $86.88 score 5138
Intel Pentium G4620 3.7GHz2 core 51W $91.89 score 5321
Intel Core i3-7100 3.9GHz 2core 51W $106.99 score 5855
Intel Core i3-8100 4core $117 score tbd estimate at 7200-7400
Intel Core i3-7350K4.2GHz 2core 60W $123.57 score 6738

It is beat by a Pentium G4500

There aren't, despite what synthetic benchmarks indicate. You're simply can't compare a low TDP Apple ARM SoC against 15W+ general purpose x86-64 chips. ARM cores (excluding other on-die SoC stuff) are designed with less transistors, have fewer registers, simpler pipelines+decoder stage and only support 32-bit long instructions even on ARMv8. For certain type of workloads they're more efficient since the instructions are simpler, but heavier workloads will stress the core and require more cycles to complete. ARM has no equivalent to Intel's 128/256-bit SSE/AVX units which are used in games and productivity-oriented applications and trying to run the same workloads using ARM's NEON/VFP would be way slower than on x86.

If you would cram an Intel chip with a similar TDP inside the same 'mobile' thermal envelope it would obviously be limited and fall behind any modern ARM chip because performance per area (mm2) and performance per mW is not what x86 chips primarily strive for. For comparison an entire AVX2 unit on an x86-64 Intel chip takes way more transistors than an entire ARM-A50 (~40-60k transistors at 14nm) series core to implement, its successor AVX512 takes even more space than an entire Atom core (low power x86) which is itself several times larger than a Cortex A-70 series core (without L3 caches).

But if you tried to push the Apple ARM chip inside the Intel 50W+ TDP market segment where high clocks and instruction density matters, you're bound to hit a wall because the current ARMv8 ISA can't scale well there in its present state.

You really can't compare. They aren't based on the same architecture, they're not available for the same platforms, and the specs are actually pretty useless for comparing now because of IPC differences.