CC2340R5: Dynamic/Runtime configuration HFXT Cap Array

They are both adjusting the capacitor arrays with respect to the HF XTAL.

For CC26x2, the function is described in osc.h:

//*****************************************************************************
//
//! \brief Adjust the XOSC HF cap array relative to the factory setting
//!
//! The cap array factory setting (FCFG) can be converted to a number in the range 0 - 63.
//! Both this function and the customer configuration (CCFG) setting can apply a delta to the FCFG setting.
//! The CCFG setting is automatically applied at boot time (See ../startup_files/ccfg.c).
//! Calling this function will discard the CCFG setting and adjust relative to the FCFG setting.
//!
//! \note Adjusted value will not take effect before XOSC_HF is stopped and restarted
//!
//! \param capArrDelta specifies number of step to adjust the cap array relative to the factory setting.
//!
//! \return None
//
//*****************************************************************************
extern void OSC_AdjustXoscHfCapArray( int32_t capArrDelta );

For CC2340, the function is described in ckmd.h:

//*****************************************************************************
//
//! \brief Sets target HFXT capacitor ramp trims
//!
//! This function sets the target HFXT capacitor ramp trims. It will
//! overwrite the target HFXT ramp trim values set during startup.
//!
//! This trim value is used when target turning on the HFXT.
//!
//! \note The value for \c capTrim must be found experimentally based on the
//!       chosen crystal and desired ramp behaviour.
//!
//! \param q1CapTrim Target Q1 capacitor trim.
//! \param q2CapTrim Target Q2 capacitor trim.
//!
//! \return None
//!
//! \sa CKMD_O_HFXTTARG for trim range
//
//*****************************************************************************
__STATIC_INLINE void CKMDSetTargetCapTrim(uint32_t q1CapTrim, uint32_t q2CapTrim)
{
    uint32_t tmp = HWREG(CKMD_BASE + CKMD_O_HFXTTARG) & ~(CKMD_HFXTTARG_Q1CAP_M | CKMD_HFXTTARG_Q2CAP_M);
    tmp |= (q1CapTrim << CKMD_HFXTTARG_Q1CAP_S) & CKMD_HFXTTARG_Q1CAP_M;
    tmp |= (q2CapTrim << CKMD_HFXTTARG_Q2CAP_S) & CKMD_HFXTTARG_Q2CAP_M;
    HWREG(CKMD_BASE + CKMD_O_HFXTTARG) = tmp;
}

In addition to this, please note the recommended testing mentioned here : (+) CC2340R5: HFXT External Capacitor Value - Bluetooth forum - Bluetooth®︎ - TI E2E support forums