Not able to change bibliography style

[singhakr]

I am using the template provided on Overleaf (v4.3). I have tried various ways based on the documentation to change the bibliography style to plain, but it doesn't work. Either no bibliography is printed, or it is printed in default style. I am compiling the project on Overleaf and it is set to use XeLaTeX. I have tried "recompile from scratch", which should delete everything rerun the whole process.

I am also using bibend=bibtex, but not sure whether it is actually being used. I have even tried putting the style file plain.bst in the project folder.