Hello, Chinese names are translated into English, and the pronunciation should be the same as Chinese.

English name translation of "Sun";

Sun, (separated by commas between surnames)

Generally speaking, when introducing yourself in English, say "Wen Qi" first and then "Sun":

Wen Qi Sun (you don't need to write your name with a comma first)

If you want to choose another English name with homonym, you can consider:

Wenxi, Wendy, Wendell, Wandell, Winnie.

Because foreigners' pinyin pronunciation is different from ours, some people will pronounce it slightly differently or even inaccurately, but this does not affect your self-introduction. You don't need to cater to their pronunciation to introduce your name.