Yes - any MS250 model is physically stackable with any other MS250 model.
You will need at least one 40G stacking cable, of the right length, from within the Stacking Cables section here: https://meraki.cisco.com/lib/pdf/meraki_datasheet_sfp.pdf
You can't physically stack between different MS series - e.g. MS250 with any MS350. The only exception to this is that you can physically stack MS210 models with MS225 models.
None of this should be confused with virtual stacking, which is basically a GUI only feature and works for all switches deployed in the same Network in Dashboard.
https://documentation.meraki.com/MS/Stacking/Switch_Stacks
