How is /ɑ:/ realized in British English: [ɑː] or more relaxed than [ɑː]?

I know that /ɑː/ is open back unrounded vowel and is found a lot in British English. It is the vowel in bath, father, bar, car etc in British English. In American English, this vowel is found in bar, father, car (but not bath!).

But when I listen to the audio given in Wikipedia, IPA chart website and this IPA chart website, I feel that pronouncing the vowel exactly like /ɑː/ would sound stilted.

I listened to many British people when pronouncing this vowel and they do not sound like this at all to me (non-native). If I heard them correctly, they were pronouncing /ɑː/ as not [ɑː] but something more relaxed or at least not that back and long as the audios in the above websites suggest.

Bath: Cambridge Dictionary, Lexico powered by Oxford: the word "bath" is pronounced not with [ɑː] but something more relaxed than [ɑː]. I tried to pronounce it with [ɑː] but it sounds unnatural.

Question: Do British people usually pronounce /ɑː/ as [ɑː] or relaxed and shorter than [ɑː]? Am I hearing them correctly?