Can strain (stretch) or other abnormal pressure in vegus nerve cause change in base line heart rate to 120 bpm?

It is opposite: Vagal stimulation causes opposite response. It produce bradicaldia ( low hr), not tachycardia, as you described.

A heart rate of 120: A heart rate of 120 BPM reflects a slight increase in adrenalin. It is important to note that it is easy to get a heart rate of 120 bom, often by just thinking about your heart beat. Most abnormal arrhhythmias cause an increase in heart rate to over 150 or 200 bpm.