Band locking experimentation - locking one band at a time (3,1,20) - and noting the CellID for each and if they all convert back to the same eNB on the cellmapper calculator then that'd mean the mast has those bands. You can't check B32 like this though, as it is downlink only and wont work on its own but should be able to enable B20+32 and if that results in 4G+ then B32 is present on the same mast as the B20 one.
Or, a (very zoomed) photo of the feeders into the bottom of antenna might give an indication, assuming they are suitably labeled.