What is the default block size when selecting evenly present items with block randomisation?

I have conducted a remote RCT on Qualtrics where participants were randomized to receive one of two interventions. I did this by setting up block randomization with the intervention delivered on the final screen. For the write up I need to report what the block size was to determine randomisations (e.g. after X allocations the results were even). Does anyone know where to find this? I have trawled through all the help sheets but can’t find it anywhere.