Since macOS 10.15 will remove support for 32bit binaries, it might be time to start preparing for this as a user. Steven Troughton-Smith linked to this older article from last year:
macOS High Sierra 10.13.4 gets us a step closer to ditching 32-bit mode for apps. In fact, you can force your Mac to run only in 64-bit mode if you aren’t afraid to pay a visit to the command line.
This way, you can see if any applications you use are 32bit, and if you can live without them – if not, you can start looking for alternatives.
Disabling 32-bit mode is an elaborate way to find out what applications are 32-bit. Instead, run macOS’s System Information and look in the Software > Applications section. All applications are listed there and there’s a 64-bit (Intel) column you can sort by to see all the applications listed with “No.”
You can also create a savable list of 32-bit apps using the command line:
system_profiler SPApplicationsDataType | grep -B 6 -A 2 "(Intel): No" > ~/Desktop/non64bit.txt
Since the advent of 64 bit mode years ago, you can simply hold down ‘6’ and ‘4’ to force boot into 64 bit mode. And you will remain in that mode until you reboot holding down ‘3’ and ‘2’ to force 32 bit mode.