When changing to another crankset , do I need to change to the brand's specific bottom bracket?
It appears that all 1x Shimano XT cranksets are Hollowtech 2, two piece cranksets which require outboard bearing bottom brackets specific to Shimano's Hollowtech 2 system.  Shimano's compatibility chart points out that 1x drivetrains require different frame spacing.  The rear dropouts of a compatible bike would be 142 mm or greater, allowing space for the larger number of rear sprockets.

If your mountain bike has the more common 135 mm spacing between the rear dropouts, you could use one ring of a compatible crankset. There are several tips for doing so on this site and others.

To answer your question specifically, yes cranksets require a specific bottom bracket, especially so the new offerings from SRAM and Shimano and others.  The Suntour xcm utilizes a cartridge bearing bottom bracket with either square taper or Octalink spindle interfaces. The 1x XT crankset utilizes a different type as described above.