All Raspberry Pi 4/Pi 400 boards are 64-bit, however they will report themselves as 32-bit when using the normal Raspberry Pi OS as the standard/default operating system is 32-bit.
A 64-bit version of the operating system is also available and can be selected as an option when using Raspberry Pi imager.
The default 'go-to' image is still the 32-bit version, so this is what we ship with our SD cards and kits.