After you purchase a resource plan, you cannot change the type of the resource plan.
For example, you cannot change a Standard (LRS) storage plan to an IA (LRS) storage plan after you purchase the Standard (LRS) storage plan.
If you want to use an IA (LRS) storage plan to offset the storage usage of Infrequent Access (IA) locally redundant storage (LRS) objects, you must purchase an IA (LRS) storage plan.