Otdfbt

I want My journal wants author names to be abbreviated as "Lastname, FS" in the bibliography, but haven't found a way to do this after some excessive searching. Does anyone know if this is possible?

Here is MWE that shows how I don't want it to be

documentclassarticle
usepackage[backend=biber,giveninits=true]biblatex
DeclareNameAliasauthorlast-first
addbibresourcejobname.bib
usepackagefilecontents
beginfilecontentsjobname.bib
@bookkey,
 author = Lastname, First Second,
 year = 2001,
 title = Title,
 publisher = Publisher,

endfilecontents

begindocument
citekey
printbibliography
enddocument

Result:

The option terseinits does that for you. terseinits is a meta-option that essentially executes the following definitions

renewrobustcmd*bibinitperiod
renewrobustcmd*bibinitdelim
renewrobustcmd*bibinithyphendelim

and sets the test ifterseinits (that test is not used by a lot of styles, apparently, so it hardly matters).

If you want a more fine-grained control, you can redefine these macros yourself. They do pretty much what their names suggest: bibinitperiod is the punctuation after a name initial, bibinitdelim the space between two name initials and bibinithyphendelim replaces the two between hyphenated name parts such as Jean-Jacques.

documentclassarticle

usepackage[backend=biber, giveninits=true, terseinits=true]biblatex
DeclareNameAliasauthorfamily-given

usepackagefilecontents
beginfilecontentsjobname.bib
@bookkey,
 author = Lastname, First Second,
 year = 2001,
 title = Title,
 publisher = Publisher,

endfilecontents
addbibresourcejobname.bib

begindocument
citekey
printbibliography
enddocument

Note that I changed the deprecated last-first to the new family-given, since you are already using the new name giveninits (cf. Biblatex 3.3 name formatting).

If you are using authoryear, you may want to redefine sortname and not only author:

DeclareNameAliasauthorfamily-given