Temperature at 2 m MERRA2
When I visit that link, the first option at the top ("Data Product") defaults to inst3_3d_asm_Np, which is atmospheric variables in pressure levels.  I suspect you need to change that dropdown option to inst1_2d_asm_Nx, which is surface and near-surface variables.  The list is shows me for that option is,

DISPH = zero plane displacement height
PS = surface pressure
QV10M = 10-meter specific humidity
QV2M = 2-meter specific humidity
SLP = sea level pressure
T10M = 10-meter air temperature
T2M = 2-meter air temperature    &lt;---- Here it is!
TO3 = total column ozone
TOX = total column odd oxygen
TQI = total precipitable ice water
TQL = total precipitable liquid water
TQV = total precipitable water vapor
TROPPB = tropopause pressure based on blended estimate
TROPPT = tropopause pressure based on thermal estimate
TROPPV = tropopause pressure based on epv estimate
TROPQ = tropopause specific humidity using blended tropp estimate
TROPT = tropopause temperature using blended tropp estimate
TS = surface skin temperature
U10M = 10-meter eastward wind
U2M = 2-meter eastward wind
U50M = eastward wind at 50 meters
V10M = 10-meter northward wind
V2M = 2-meter northward wind
V50M = northward wind at 50 meters