Same here with a 3600X, 2060 Super, and 16gb DDR4. Got through the fight using the following:

1. Windows - Run DX11 version
2. Windows - Windows 7 compatibility mode
3. Windows - Disable full screen enhancements
4. Game - Turn all graphics settings to lowest possible
5. Game - Turn off all graphical enhancements
6. Game - Lower the resolution to smallest possible (640x480)
7. Game - Turn sound all the way down

This seems like a memory allocation error with the vast number of objects the game creates, so shrinking the memory footprint using the lowest settings should work. Even with these settings I had to make sure I killed all of the enemies to prevent a crash. Thankfully there is a savepoint right next to it, but hopefully this gets corrected at some point.

Also, you don't need to use the Red Clocks to deal massive damage. Any clock will do.

Renaming the .dll (which basically makes you use the Windows 7 one in DirectX 12 mode) fixed it for me during the main game. During the arcade mode where you can refight Anchor the only workaround for me was making sure I instantly killed the Hiss that spawn just before Anchor's first attack. As long as at least one of them is dead /despawned before it launches the attack it will not crash.

I also take the liberty of posting my return for other people who are in the same situation as me.

The crash is also very present on Linux (in DX11 as well as DX12) and even possible to reproduce it when opening the game (but it is very rare).

Hey, I had to give up everything else and go with this. The rest of the game was definitely worth shortchanging that fight though

Had 100% CTD on Anchor fight, too. Use One-Shot option. A pity but better than the alternative.

Tried a bunch of things from this forum and this one worked for me, Win10 RTX2070 Super, DirectX12 version.

Just an FYI this will likely not work in the DLC "arcade mode" where you can refight Anchor. The solution then is to make sure you IMMEDIATELY kill the hiss that spawn at the beginning of the fight before Anchor shoots the mouth-beam. You have about 1 second between it firing and them spawning to kill one. Basically the game will crash if there are certain amount (maybe more than 2?) hiss in the fight when it is launching that attack.

Also if you could please kindly share your version of Windows 10 that you are using.

Windows 10 Family edition version 2004.

I don't currently plan to do the arcade mode DLC but I'll keep this topic handy if I change my mind, thanks!

The first time I started the fight, I got a CTD when the Anchor started it's first attack.

Then, I don't know if that was pure luck or just made the difference, but the second time I tried to never point the camera at it when it was attacking, and I beat it without issues.
I took my time so it made more than 10 attacks and I had to kill many hiss, I just turned the camera to the walls behind me every time the Anchor started to charge an attack.

This is ridiculous. I've tried every single suggested fix and even one-hit kills doesn't solve it for me, it still crashes before it can register a hit. How is this not fixed after 6 months?

Just shoot with explosives when it starts to open itself

Ok, thanks it just didn't work, but after lots of tries with lowest setting suddenly game didn't crash and I destroyed the boss. Shame that this is not fixed after so much time.

in the option menu check the game setting at the bottom

I had to do it too for that boss, nothing else worked.

It's good I was able to do the boss after finishing the main story but it would be nice to inform Remedy that the boss may not be playable in side quest during the game without finishing the game for an unknown reason the game crashes on this boss as said several people on the forum page I had exactly the same bug crash when the boss arrived or after several minutes.
I had removed all the resolutions and played in windowed mode with the lowest resolution possible. I removed the subtitles and tested the controller vibration with directx 11 and 12. I couldn't remove this bug even when playing in the main administrator mode and after finishing the main story I came back to the boss and was able to finish it with the ultra resolution without any problem or bug.

My setup:

Windows 10 Professionnel 64 Bit
MSI Z170A Gaming M5
Intel Core i7-6700K (4.0 GHz)
4*8Go RipJaw G Skill 2400 MHz, CAS 15
CORSAIR iCUE H100i Elite Capellix
GPU - KFA² 1070 EXOC Sniper 8Go
SSD - Samsung 850 EVO 500Go