MGSD is more demanding than a typical UE5 game, but it's still much less demanding than for example Black Myth: Wukong with PT. Also, let's not forget that the MGSD doesn't have any stuttering issues, which is a significant achievement for this engine.
My RTX 4080 Super allows me to play MGSD at solid 60 fps with just DLSSPerformance at 4K. I would need to use FGx2 on top of that in Black Myth Wukong in order to get over 60fps. With DLSS balance the game also run very well, I get 60 fps literally 99.9% of the time, and only shooting fuel barrels can cause the framerate to dip below the 60 fps cap. Furthermore, even DLSSQ doesn't change the experience that much because the fluctuation between 50 and 60 fps isn't making a noticeable difference on my VRR monitor. It boggles my mind that people use VRR screens and still want perfectly locked 60 fps, even in slow-paced games that should be played with a gamepad.
4K DLSS-Quality, Ultra GI, Ultra Textures, Shadows set to high.
I also tried locking the framerate to 40 fps with RTSS (using the Reflex Limiter), and I must say that I wouldn't mind playing like that if my PC couldn't deliver more fps. Game is responsive and look smooth during camera panning with at least 40fps. There's however a huge difference at 30 fps because even slow camera panning show jumps between frames, so framerate no longer look smooth. Unless you really have no choice, I wouldn't recommend playing MGSD at 30 fps. A satisfactory experience in this game is provided only by 40 fps and above.