I would like DOI to appear while using the agsm bibliography style. One solution suggested is to alter the .bst file (see hack for including doi in agsm bibliography style) but working on Overleaf, that is not appropriate.
Another solution would be to use the plainnat bibliography style, but then the first name appears before the last name, and to change that, you need to modify the .bst file too (Displaying author's name in a bibliographic entry in the form: Surname, First Initial of Firstname).
Is there a way to solve this issue without modifying the .bst file? Or is there an easy way to modify it on Overleaf?

.bstfile approach' on Overleaf: Usually you can get the.bstfrom CTAN. You could then modify it on your machine and upload the.bstfile to your Overleaf project, where it will be picked up by BibTeX and can be used as expected. – moewe Dec 09 '20 at 15:01.bstfiles if you want to change the output of a BIbTeX style (some styles are customisable with macros from the document preamble to some degree, but not in a way that adds support for new fields). An alternative would be to work around your style not supporting adoifield and using a general-purpose field (as is often done for URLs with the BibTeX base styles), but again, that doesn't feel nice. ... – moewe Dec 09 '20 at 15:09biblatex(which is a little more complex than just changing the style),biblatexcan be configured with TeX code in the preamble of your document, so there is no need to mess with any.bstfiles. – moewe Dec 09 '20 at 15:12bath.bst: The treatment of DOIs and omission of ISBN is coded into the.bstfile. If you want to change that, you have to modify a copy of the.bstfile. As mentioned before, generally you should expect having to modify the.bstfile to change the output of a BibTeX style (there are some exceptions for common modifications in some styles, but usually not for bigger things like this). – moewe Dec 11 '20 at 07:50