Does my Galaxy A71 support Dex?

The A series of phones don’t support DeX. Only the S series, Note Series and Fold have the Samsung DeX service.

For a list of mobile devices that support DeX, you can refer to this link:

https://help.content.samsung.com/csweb/faq/searchFaq.do?serviceCd=sdex&category1_id=sdexb10300&r_faq_id=159242&_common_country=AO&_common_lang=en_gb