Hi @annacupofcoffee,
I hope you are well today and thank you for your question.
Have you tried using the solutions posted in the following topics?
https://colorlibsupport.com/t/define-sizeformat-of-featured-image-on-home-page/
https://colorlibsupport.com/t/featured-image-no-longer-square/
Best Regards,
Movin