Sorry, but the editor and publisher decide when a magazine article will be published. Not the author nor the person being interviewed.
Just in case you need to learn how the process works: www.encyclopedia.com/media/encyclopedias-almanacs-transcripts-and-maps/magazine-industry-production-process
CBS decided when the interview was going to air. Meghan did not go to Oprah and say hey? Prince Philip is going to die in a few days we should run that interview on TV.
Rumors of an interview started in November 2020. In January 2021, the rumors intensified. CBS confirmed the rumors of an interview on February 15th 2021.
Prince Philip was admitted to the hospital on Feb 16th. The Palace reported: “The Duke’s admission is a precautionary measure, on the advice of His Royal Highness’s Doctor, after feeling unwell.
“The Duke is expected to remain in hospital for a few days of observation and rest."
Oprah's interview aired on March 7th on CBS
On March 16th, it was reported that Prince Philip was successfully treated and was returning home.
Prince Philip died April 9th, a full month after the interview. Not a few days, not shorty before. A month.
So no, Meghan did not plan the interview in order to hurt the royal family surrounding Prince Phillips death.
FWIW, my grandmother died when I was 13 years old. All I remember is it was October. I was her favorite grandchild.
I remember exactly where I was and what I was doing when Princess Diana died. I never remember the day until the media tells me it is coming.