It's really interesting if you look into the studies that have been done on how people's heart rates can rise due to mental stress. I think there were several done on people giving presentations, and if IIRC a lot of the people in those studies went a lot lot higher than 120. Also there was a really interesting one done on musicians giving performances that one of them (a pianist) actually exceeded their maximum (predicted maximum) heart rate. I cba to dig for more but here is that study: https://occup-med.biomedcentral.com/articles/10.1186/1745-6673-3-16

I myself had a heart rate of 208 BPM once in a hospital at rest just from anxiety, even though my predicted maximum at the time (220 minus age) was only 201. I got really worried about it until I started reading lots about the topic. I remember there was a study on race-car drivers before a race that showed they were at like 180bpm before the race even started, one on a teenage girl in the audience of a pop concert where her rate went to something like 200bpm, just a whole bunch of interesting ones.