Thank you Mr. Perry and Mr. Anthony. for yours valuable comments
I will disable custom TLOG backup in Principal database server during configuration of log shipping.
Does Log shipping technique will take of LDF growth size? So normal TLOG backup will truncate unused log space in LDF file and reuse it again,  that will be managed log growth rate. Please suggest.

RPO and RTO are 4 hours defined and approved by business side. for recovery server and database both.
My assumption data bit loss duration of 15 min because  log shipping TLOG backup schedule at every 15 min.
If primary principal database server failure, then data available on both the location Mirror server as well as DR setup server with 15 min gap.

Thanks