SD certainly won't but even a bit starved FHD content won't look 4k per say but halfway as close as 4k on a very good upscaling TV. Regarding CX Processors I would politely disagree with you.A good picture processor can upscale to a certain extent and LG CX has a good one. I think the X1 ultimate in Sony not withstanding this is pretty decent. SD and 1080 fhd content will not look 4K no matter what even if it is the best of the best of the best in TVs.
You see at the time when I brought my CX I was so firmly entrenched on the LG OLED bandwagon n so convinced by all the OLED hype that I refused to even check out the competition, what a big mistake that was.
Couple of months later when I visited a friend to check his Samsung Q95T I was in for a big surprise, the same bit starved FHD looked noticeably sharper n cleaner on his set n HDR was the biggest difference, when I watched a few clips from Aquaman n Madmax I was like wow so this is how HDR is supposed to look like.