I haven't seen reports confirm this (only for the A19 chip) so I just bought a new M5 MacBook Pro 14" and did this:

  $ sysctl -a | grep MTE4
  hw.optional.arm.FEAT_MTE4: 1

MTE4 is the "enhanced memory tagging extension"[1] that underlies Apple's broader Memory Integrity Enforcement system.

More on MIE and why it's cool: https://security.apple.com/blog/memory-integrity-enforcement/

[1] https://developer.arm.com/documentation/109697/0100/Feature-descriptions/The-Armv8-9-architecture-extension?lang=en#md454-the-armv89-architecture-extension__FEAT_MTE4