The Galaxy J7 Max features a large 5.7-inch display, but the main problem with this display regarding VR is that it has relatively low resolution. The screen comes with 1920x1080 FHD resolution, and because the screen is so very large, this translates to a low pixel density, around 385 ppi pixel density to be more exact. This leads to very poor VR experience.
If you know how VR headset work, like Google Cardboard. You know that there are two magnification lenses inside the headset. These headset are designed to allow your eyes to focus on the screen when it is positioned very close to your face. The entire view is magnified, so you can see things on the screen much larger now. When you use a Google Cardboard headset with a screen with that pixel density, you are assured to see pixelation. By 'Pixelation', I mean that the pixels on the screen are very noticeable and you don't get to see a smooth picture. This degrades the overall VR experience.
Now, I don't mean that you can't use it for VR, of course you can, but once you try it out with a low pixel density screen you know what I am talking about. I tried to use it several times with several devices with low pixel density but I just couldn't bare the low image quality, the pixelazation on the screen. This is one reason why phones like the Samsung Galaxy J7 Max aren't ideal for mobile virtual reality. If you never tried VR before, I recommend just getting a cheap Google Cardboard or Cardboad-compatible headset for a few bucks and try it out with the Galaxy J7 Max to see whether you like it or not before you put more money on a more expensive VR headset. Of course the Samsung Galaxy J7 Max is not Daydream-ready, so using Daydream apps and games is definitely out of the question with this phone.
Of course having a higher 2K resolution would make things much better and increase the pixel density., but this is a budget phone. If you want a good mobile VR experience, you should be looking elsewhere.