I have tried to enable the APTX feature on my Note 9.
First, you'll need to enable the developers option in the Settings of your phone. (To enable, please go to Settings> About device/phone> Software information> Tap fast the ''build number'' for almost 5 times)
Once enabled, please go back to Settings> Developers option> Look for Bluetooth Audio codec and change it to APTX.
Hope that it may help!
The multi-page thread at https://eu.community.samsung.com/t5/Galaxy-Note9/aptx-HD-support-for-Galaxy-Note-9/td-p/688333 is about very frustrated users of Note 9 not having APTX with either Android 8 be or Android 9 update.
Samsung is out of line.
Andrew (moderator), stop ignoring my post or I will use the Internet to further expose Samsung for not supporting APTX
The developers have confirmed that aptX should be available on the latest Samsung smartphone devices - including the A70.
As for specific versions, aptX HD was found to be suspectible to audio chopping whilst streaming during the developers' tests, so they've opted to implement aptX Adaptive support instead. Nothing definitive from them in the 'when' that will be implemented though, but likely to come in a future software update.
Say "Hello!" to the Community in The Introduce Yourself Thread.
Even if timescaled not definitive yet, good to know that APTX will be supported in the adaptive format in due course, though pity problem with the HD. Some technical information here: