A 64GB card is enough for the base game (10GB), update (1GB), save data (2MB), and a few other titles. For a modded library, 256GB+ is recommended.
Many power users ask: Should I find a pre-patched XCI that includes the update? pokemon lets go pikachu switch nsp xci upd work
Before starting, it is crucial to understand what the different file types mean. A 64GB card is enough for the base