Tv audio and b/t audio at the same time

Some TVs allow this directly, if yours does not then I think you will have to use an audio extractor placed inline between the TV and soundbar, like https://www.amazon.co.uk/Extractor-Splitter-Optical-Converter-Amplifier-4K60Hz-444-18G-4KCVH2H/dp/B07GZGDYQX/ref=sr_1_6?dchild=1&keywords=hdmi+audio+extractor+4k+60hz+bluetooth&qid=1617119631&s=electronics&sr=1-6 . I only had a quick look but couldn't find any that also do Bluetooth out so the most likely is that you need to add bluetooth adapter with SPDIF/Toslink input as an output.
Main things to watch for are making sure the extractor passes through the right video signal (HDR, 4k@60/120 etc.) and the Bluetooth adapter has Aptx-Low Latency (as should your headphones).

This might work, https://eu.community.samsung.com/t5/tv/multi-audio-output-not-available/td-p/460901 . I don't have a samsung tv so can't be more accurate, if you don't see the described option for multi-out then it's not supported and you'll need to go the HDMI splitter + bluetooth adapter route.

I have this function on my LG TV. It also has settings to deal with the latency issue... Also sennheiser Momentum headphones also have a codec that reduces the latency between the headphones and the TV (specifically for that task)