You need a receiver that supports Dolby Prologic II/IIx/IIz. Your PC sound card will connect to the receiver with 2 channel stereo, preferably SPDIF. The receiver will upmix the audio to your 5.1/7.1/9.1 speakers.
You should be able to select gaming mode in the receiver for best results in terms of channel separation. Windows should be set to 2 speaker configuration in the control panel and sound card driver.
If the game supports matrixed Dolby Surround, the receiver should have an indicator that detects the input is matrix encoded.
If you don't see the indicator, check the game setup options and enable Dolby Surround.
Win 11 - Intel i7-1360p - 32 GB - Intel Iris Xe - Sound BlasterX G5