$120k in SF probably amounts to take home just under $6k/mo. $4k goes to rent, so you have $2k for everything else.
That's not a great QOL. For comparison, I ran the Mexico City / SF cost of living on Numbeo[0]. $38k in Mexico City would need to be $140k in SF for comparable quality of life.
(side note -- this COL calculator is super neat! anyone have any evidence of the accuracy?)
[0] https://www.numbeo.com/cost-of-living/compare_cities.jsp?cou...