The guy who did this (@pheonixmario) tried to help me, but I still have zero idea on how to do it and make the player smoothly walk in. If anyone can help, I would appreciate it immensely.
That is definitely arguable. The method by @EgoMoose is likely to have the exact functionality that you are looking for, and the thread provided has the discussion that you are looking for.
You cannot get the quality from the post you linked with viewports. They use the glass glitch which Roblox has specifically said not to use as they intend to fix it.
I don’t understand entirely what you mean, but regardless. Aside from resolution, things like lighting and post processing dont apply to viewport frames so you’ll never have that type of quality.
Hey @mobyboyy, ik that you maybe not more want achieve this effekt, but i hope this video will help you (and this was made in unity, but it can be addapted into Roblox, it only was a tutorial):