Sometimes in regards to using it to have it as a default for pictures when the camera app is first launched after inserting the Sd card it auto asks if you want to set it as default.
In regards to Apps if your device allows it then after downloading the App then go into your Apps section and look for storage to see if that app can be manually moved from the devices storage to Sd card.
Current Phone ~
Samsung Note 20 Ultra 5G SM-9820 _256Gb SnapDragon 865+
Samsung One Ui 2.5/ Android 10.