Group of SSBs is called SSB Burst. SSB burst is transmitted within the half frame of total frame. again this SSB burst repeats with a periodicity which is signaled by higher layer parameter ssb-periodicityServingCell.
The size of SSB burst can be 4/ 8/ 64 SSBs based on the frequency and Sub Carrier Spacing.
So max size of SSB burst possible in NR is 64 for frequency > 6Ghz and SCS = 120kHz/240 Khz.