You may have to use external memory to store the framebuffers used by LVGL. These can become really big.
For instance, a 480x272 display with 16-bit color depth already takes 261KB, you probably will not be using the entire display size for a display buffer… perhaps divided by 8, but that’s still ~32KB.
However, your mcu has 8M RAM… that is really quite a lot, so you should not be running out. Decrease the size of your display buffers first.
EDIT: as far as I can tell, the 8M RAM is external, so you will have to store those buffers in external PSRAM. I have no idea how to do this on Espressif MCU’s, you will have to do your own research there.
You completely lack information , what IDE you use, how partitions config for flash usw. Arduino ? VSCode ? …
ESP default config use little APP partition and you can see 71%, but changing one file and you see 15%