So looks like HBO is working on a fourth season, according to Deadline:
‘True Detective: Night Country’ In The Works At HBO From Issa López & Barry Jenkins
HBO is working on a fourth iteration of True Detective. Deadline understands that the WarnerMedia-owned cable network is developing a new take on the crime drama – tentatively titled True Detective: Night Country – from Issa López and Barry Jenkins. We revealed in February 2021 that HBO was in...
deadline.com