Rendering Partially The Display

I use NXP IMXRT series MCU and LVGL v9 for now. I have 800x480 resolution display.

I would like to update my screen partially to gain from memory. I want to divide my screen into 3 parts from top to bottom as 120w800h, 240w800h and 120w*800h. I have visual design according to that but have no configuration on software side. Can someone give me clues to have framebuffers, lv_display_t object and updating screen via flush display function.

I want to know something related above question. Is it possible to update spesific areas of the screen(as an example above half will be updated, below half will not) with using dual frame buffer(both are full sized of the screen) ? If possible, which one is faster, refreshing half screen with dual buffer or having 2 different frame buffer for above half and below halfs and refreshing them partially ?

Your idea is based on display type. Have your display memory or not?
LVGL prefered update is partial , then you only need learn basics