IBM has a history of this kind of stuff - when they need to expand: Remote work schemes, and flexible work hours become more common. When they need to tighten the belt, the first step is a RTO. So long as you are willing some flexibility in the time line, and support employees in the move - it will lead to plenty of people quiting, a few people moving, then you do a small round of layoffs avoiding people who willingly moved closer to the office etc as these are people unlikely to have quick new opertunities and are more stuck with the company/loyal to it.
The Pandemic is not the first time IBM has done something like this, and it won't be the last.
Now, if we really get into the weeds - a lot of Companies that know this can be pulled off REALLY DO NOT want Remote work/hybrid work schedules to become industry norms, as once they do - these practices for ridding your company of say 1-2% of it's staff periodically stop being viable and you need to go for a more traditional layoff scheme.