copy contacts from mobile phone (Andriod 11) to thunderbird address book

Thunderbird can import contacts in vCard (VCF) and CSV formats. If your phone can export your contacts in one of those formats (I recommend vCard), and you are able to transfer the resulting file to your computer, Thunderbird can import them into its address book. This article describes how (use the "import from a file" option.) https://support.mozilla.org/en-US/kb/thunderbird-import