It really depends on what the 1080p content is, what the encoding is and what bitrate it is. For example, Mirzapur season 2 on prime video is in 4K, but the video quality is horrendous with a green cast in dark scenes, low bitrate blocking artefacts and so on. On the other hand, the Expanse Season 4 on prime video looks sublime with a very similar bitrate at 4k.
Generally, Indian content is encoded poorly because our directors/producers focus more on creating controversies to drive sales than focus on content and quality. I have copies of 1980s Hollywood movies like Back to the future which will blow most of 2000-2010 Indian movies out of the water in terms of quality.
Please try these settings:
Standard mode, backlight as per choice, local dimming high, brightness 50, contrast 50, saturation 47-50, Sharpness 0-10, Adaptive contrast off, Noise reduction low, Temperature Standard. The content will look a lot more natural this way.
REMUX is basically muxing the same file again. MKV format can take one video track, multiple audio tracks and multiple subtitles all in a single file. No need to keep separate SRT files and no need to make folders as the video file itself will have your subtitles. Please PM me over the weekend, I can guide you how to do that over a screen sharing session.
Yes, Plex is the best way to consume local content. If you haven't used Plex, you're missing out a lot.