I am not sure you can specify the default as list view but if your Moodle version is 3.8 or 3.9 then you can restrict the views so they only have the option of list view if that would work for you - from Site admin> Plugins> Blocks>Course overview
General help
Course Overview Block
ການສົນທະນາຖືກລັອກ ດັ່ງນັ້ນ ທ່ານບໍ່ມາສາດຕອບກັບມັນ.