Replace example
with your store name
https://example.myshopify.com/admin/bulk?
resource_name=Product&
edit=
metafields.global.size_chest-xs:string,
metafields.global.size_chest-sm:string,
metafields.global.size_chest-md:string,
metafields.global.size_chest-lg:string,
metafields.global.size_chest-xl:string,
metafields.global.size_chest-xxl:string,
metafields.global.size_arm-xs:string,
metafields.global.size_arm-sm:string,
metafields.global.size_arm-md:string,
metafields.global.size_arm-lg:string,
metafields.global.size_arm-xl:string,
metafields.global.size_arm-xxl:string,
metafields.global.size_back-xs:string,
metafields.global.size_back-sm:string,
metafields.global.size_back-md:string,
metafields.global.size_back-lg:string,
metafields.global.size_back-xl:string,
metafields.global.size_back-xxl:string&
metafield_titles[metafields.global.size_chest-xs]=Chest_XS&
metafield_titles[metafields.global.size_chest-sm]=Chest_S&
metafield_titles[metafields.global.size_chest-md]=Chest_M&
metafield_titles[metafields.global.size_chest-lg]=Chest_L&
metafield_titles[metafields.global.size_chest-xl]=Chest_XL&
metafield_titles[metafields.global.size_chest-xxl]=Chest_XXL&
metafield_titles[metafields.global.size_arm-xs]=Arm_XS&
metafield_titles[metafields.global.size_arm-sm]=Arm_S&
metafield_titles[metafields.global.size_arm-md]=Arm_M&
metafield_titles[metafields.global.size_arm-lg]=Arm_L&
metafield_titles[metafields.global.size_arm-xl]=Arm_XL&
metafield_titles[metafields.global.size_arm-xxl]=Arm_XXL&
metafield_titles[metafields.global.size_back-xs]=Back_XS&
metafield_titles[metafields.global.size_back-sm]=Back_S&
metafield_titles[metafields.global.size_back-md]=Back_M&
metafield_titles[metafields.global.size_back-lg]=Back_L&
metafield_titles[metafields.global.size_back-xl]=Back_XL&
metafield_titles[metafields.global.size_back-xxl]=Back_XXL