Try disabling intgrated Intel GPU.

Fair point. Yeah, the Ultimate Performance plan basically raises the power limits, at the cost of more voltage and more heat.

As I haven't had this issue anywhere with my desktop 3080, I cannot say what causes it, but my guess is something during character creation hits a part of the GPU too hard, causing either the voltages or temperature to spike higher than your system can handle.

If the game only crashes, with no system shutdowns og bluescreens, it's likely not a power delivery problem, and given the error logs something happens to your RTX 3070 specifically.

Could you again try with HWMonitor running, just to see if anything is raising any red flags regarding GPU temperatures or voltages?
https://www.cpuid.com/softwares/hwmonitor.html

I recommend running the game in windowed mode, with HWMonitor on an external monitor if you have one, so you can see what happens in real-time.

To be blunt, this is why I personally don't like gaming laptops - they are certainly techically impressive for what they can do in such a small package, but they are also inherently limited in terms of power delivery and heat dissipation. Which is not a good combination for gaming.

So I actually started the game with the Integrated Graphics and saved it after the intro, then loaded back up with the 3070 enabled and it let me play a little further but eventually crashed again (wasn't long though).

I was running the game in windowed mode while running HWMonitor and the voltage at 0.900 V and MHz at 1755 seem to max out as soon as the game gets going but the GPU utilization and Video Engine stay at 0.4% while the Memory is at 43.9%. The heat doesn't seem to max out, sitting around 67.3c

To be honest, I'm not really sure what to look for. The shop told me to run OCCT and look for errors in the test, the test just says error found but I have no idea what those errors are.

I know what you mean about the gaming laptop, I travel a lot and use it for work so need the portability.

I've attached a screenshot of the results.

I had a look at that screenshot, and there wasn't anything that immediately stood out.
Temperatures were fine, and when I checked my own Performance tab in HWMonitor, I had a "1" on everything - all the limits.had been exceeded at some point. And I still haven't had any crashes.

Sorry, can't help you with OCCT, I haven't used that program in ages.

Say, does MSI Afterburner work with your laptop? I still think it's a spike load of some sort that is hitting a limiter on the GPU too hard. If you try to underclock it (lowering the frequencies, not just the voltage), giving it more headroom, maybe it works. But I'm just guessing at this point.

Wouldn't also hurt to seek support from GOG. Maybe they will find out something in logs we are missing.
Also Witcher 3 had some problems with multi GPU setups. Could be worth exploring that.

Just got an email from the shop with the test results from OCCT and they said to return the laptop for a replacement...faulty GPU!

Many thanks to you both for trying so hard to help me with this and sticking to trying to find a solution!