Recommend a few fresh modern poems or songs adapted from ancient poems, such as Jia Xu, with soft tunes.

This is much more, and the ancient folk songs in the south are of this type.

Ancient times: songs of the Western Zhou Dynasty and midnight songs. A lot of things can't be remembered at the moment. I suggest you search "Folk Songs of Southern Dynasties", all of which are soft and beautiful.

Modernity: Both Xu Zhimo's and Lin's poems have this feature. Go to "China Poetry Library". There are their masterpieces in it.