The Shi’ah have many sects of whom are kafirs who worship ‘Ali RA and Fatimah RA, al-Husayn and others. There are also others among them, such as the Imamiyyah – the Raafidi Ithna ‘Ashari – who worship ‘Ali and say that their imams are better than the angels and Prophets.
The mildest among these are those who say that ‘Ali was better than the three (Abu Bakr, ‘Umar and ‘Uthman). The Shi’ah are of different levels and types.
Anyone who reviles the faith, or does not pray, even if he says that he is a Muslim, is not a Muslim and the same goes for one who mocks the faith or the prayer or zakah or fasting or Muhammad ﷺ, or who disbelieves in him, or says that he was ignorant or that he did not convey the message in full or convey the message clearly. All such people are kafirs.
Listen to this series for more details and to have a basic idea about this sect.