For owners of video cards 40 and higher.
1. Update DLSS to the latest version. This can be done manually or via the DLSS Swapper utility. (don't forget to update DLSS_G, frame generation.)
2. In the Nvidia App, add MGSDelta.exe and turn on the option - Smooth motion.
3. Start playing.

You will still have a lock at 60 fps, but the smooth motion option will add fake frames that will increase your fps x2 times. (Personally, my fps fluctuated from 90 to 120, very smoothly and no noticeable stutters, the most important thing is that there is no slowdown in the game.) A small input lag will appear, which is more noticeable on the keyboard and mouse. The input lag will be greater if your initial fps is already too small.

To turn it off, go back to Nvidia App, select MGSDelta.exe and turn off Smooth Motion. Happy gaming. Kojimba is a genius.

Upd.
For those who don't know how to update DLSS manually.
In UE games it is located in a separate folder.

DLSS itself is located \Steam\steamapps\common\MGSDelta\Engine\Plugins\Marketplace\nvidia\DLSS\Binaries\ThirdParty\Win64

DLSS_G
\Steam\steamapps\common\MGSDelta\Engine\Plugins\Marketplace\nvidia\Streamline\Binaries\ThirdParty\Win64

https://www.techpowerup.com/download/nvidia-dlss-dll/ - DLSS download the latest version
https://www.techpowerup.com/download/nvidia-dlss-3-frame-generation-dll/ - DLSS_G (frame generation)

If Smooth motion still doesn't turn on for you, try adding all 3 .exe files to Nvidia App and turn on Smooth motion on all 3 .exe.

1. \Steam\steamapps\common\MGSDelta\MGSDelta\Binaries\Win64\MGSDelta-Win64-Shipping.exe

2. \Steam\steamapps\common\MGSDelta\MGSDelta_Nightmare\Binaries\Win64\Nightmare-Win64-Shipping.exe

3. \Steam\steamapps\common\MGSDelta\MGSDelta.exe