Probably but you first need check the manufacturers ratings of how far their outputs can be elevated above mains ground which applies when using multiple units in series.
The manufacture will tell you 0V, because from the factory the output ground is tied to earth.
Only crap PSU's have a grounded output, those that are constructed to provide a decent featureset, their outputs can be elevated considerably above mains ground, limited by PCB clearances and component limitations.
In many cases they are easily modified to change this though. When playing around with cheap surplus stuff the easiest way to find out is to just try it, if it fails, scrap it and start over with something else.
Or in the first instance use an instrument made for the job, or relevant to our discussion a multichannel PSU designed to have channels placed in series (or Parallel) and allow for several units configured this way placed in series, all with none of their outputs tied to mains ground !
Some time ago I contacted Tech support for clarification of the SPD3303X-E datasheet Insulation specification on P4:
https://siglentna.com/wp-content/uploads/2020/10/SPD3303X_DataSheet.pdfInsulation: Case to Terminal ≥20MΩ (DC 500V), Case to AC line ≥30MΩ (DC 500V)
I was informed multiple units could be used in Series not exceeding the insulation rating.
Tech support also sent me pictures of two 30V 3A units configured to provide 120V !