Hi @Colin131195 Unfortunately Android 11 not available for the J4 Plus. Even the S9 and Note 9 not the Android 11 list. The J4 Plus been on biannual security updates since 2021. see more information here https://www.gottabemobile.com/samsung-galaxy-android-11-update-info-2020/
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB
One Ui 5.0,Android 13 .