Most apps these days can't be moved to the SD card, because they either were developed by someone who knows that they won't run from the SD card (many apps and many classes used to develop apps won't), or because it was "made" by an "app writing app", that uses a class that won't run from the SD card, so it turns off that capability, so the "developer" doesn't complain to them that s/he used their app to make an app and it won't run.
Keep apps in internal storage and use the SD card for files. (If it's a 16GB phone, it's a few generations out of date. Even a 32GB phone is a bit small for 2020. That's why people buy new phones - Android keeps getting larger, so there's less space in the phone for your apps.)