How much better will a 2160p remux look on a Full HD TV?

I always watch 1080p remux movies on my 50 inch Sony TV which only is Full HD from 2014. The picture is very nice. Will there be any (noticible) differences if I start to watch 2160p remux on this TV?

As far as I know, there should be. Because you have a very netter picture with a higher bitrate, which gets shrinked down so 1080p, but looks better than the 1080p. Because on a 1080p remux there is still "room for Moore", which gets filled on a 2160p remux.

Can I normally play the 2160p remux on a VLC placer? My pc is old..