Is there a TCXO populated on your board, or is there a 4-pin crystal as the schematic seems to show the default component selections configured for?
See figure 4-2 of the SX1261/2 data sheet
The depicted schematic shows a configuration for an external crystal, with DIO3 not connected to what is basically a ground pin on a crystal; conversely for a TCXO XTB would need be disconnected.
What is your goal here? Are you attempting to write a firmware from scratch, or to modify the module internals by reworking the components?
If a TCXO is fitted and you don’t enable it in software, I don’t think the board is going to work, conversely if you do enable it when it is not fitted, you should seemingly get an XOSC error which will not clear.
My suspicion is that a TCXO is in fact fitted and the circuit and factory code are configured for that, and unless you are seeing excessive current drain in sleep mode, it’s already being correctly controlled. But I could be wrong.