Qualcomm chipset X8 and X9 are supporting LTE 02 streams, mean UL MIMO 2x2.
To check which UE using X8/X9 chipset, using Phone Finder results - GSMArena.com
About 87 phones.
Very few handsets tm2, tm4 can be used in Uplink.
Any IE there for UL MIMO?
Interesting. I doubt that any of these phones supports UL MIMO 2x2. Need hard evidence. Very often capabilities available in the chipset are not realized in the UE.
Gsmarea is not best source 
But yes Qualcomm chip theory but no vendor have implement for LTE.
On https://cacombos.com you can find UE’s support UL MIMO. There is at least many CPE’s support on 5G NR SA.
Because most of UE’s do not support UL MIMO. If it support then it show UL streams in UL Band section.
And you know any commercial device support this? Haven’t seen any device support that so please tell me commercial device support 2x2 MIMO LTE upload and also then need RAN side support that too.
