Hi @Gene_Xu,
On the Code Editor window, open "lv_conf_ext.h" and add the following code:
#undef LV_FONT_FMT_TXT_LARGE
#define LV_FONT_FMT_TXT_LARGE 1
It should look as follows if you are deploying the GUI to a board. If you are using the simulator, add the code under "#if LV_USE_GUIDER_SIMULATOR".

Important note! Please make sure to save the "lv_conf_ext.h" file before generating code or clicking the green play button of the top right corner. In other words, write down the aforementioned macros, press CTRL + S to save, making sure the "Code saved!" message appears, and only then, proceed with the build. This will prevent your "lv_conf_ext.h" file from getting overwritten.

BR,
Edwin.