Is there available Audacity 64 bit ?

Is there available Audacity 64 bit so we can use many 64 bit VST plugin?

Not yet.
There’s a huge amount of work involved in just releasing 3 versions (Windows, Mac, Linux) and we don’t want to drop support for 32-bit Windows.
Please note that we have dropped support for Windows 7 (as have Microsoft), though Audacity 2.4.2 will probably still work on Windows 7.

Audacity’s competitor OCENaudio is available in 64-bit.
( It’s not as powerful an audio editor as Audacity though).

Thanks you very much, I still prefer to use Audacity

Can have both, (they’re both free).
If the plug-in you want to use is only available in 64-bit,
can apply it to the track in OCENaudio, then export as WAV,
then import that WAV into Audacity for editing.