How to connect amplifier with apple TV 4K

some connect their amp to the tv by hdmi-acr or by optical cable

or one can get a hdmi audio splitter

https://www.amazon.com/s?k=HDMI+Audio+Extractor+Splitter&crid=3UENR18XRBFDA&sprefix=hdmi+audio+extractor+splitter%2Caps%2C138&ref=nb_sb_noss_1

more

https://www.google.dk/search?q=hdmi+audio+splitter&ie=UTF-8&oe=

Apple TV →[HDMI]→ AV receiver →[HDMI ARC]→ TV (recommended setup) or Apple TV →[HDMI]→ TV →[HDMI ARC]→ receiver or Apple TV →[HDMI]→ TV →[optical]→ receiver or Apple TV →[HDMI]→ HDMI Audio Extractor →[HDMI]→ TV ↘︎[HDMI or optical]→ receiver

Set up Dolby Atmos or surround sound on Apple TV with a sound bar or AV receiver - Apple Support

Play audio in Dolby Atmos or surround sound on your Apple TV - Apple Support