I do not know of any sample letters for an urgent processing request.
In addition to link above, also see the current applicable PDI at https://www.canada.ca/en/immigration-refugees-citizenship/corporate/publications-manuals/operational-bulletins-manuals/canadian-citizenship/admininistration/general-file-processing/urgent-application-cases.html
Otherwise I am posting to caution that if the reason why Canadian citizenship is important for your job is to facilitate travel abroad, the prospect of getting expedited processing appears to be quite LOW.
This may not apply to you. And even if it does there is NO harm in making the request. Indeed, the criteria listed in the applicable PDI is somewhat more open-ended than it has been in the past.
BUT when most forum participants refer to needing citizenship for a job they are NOT really talking about needing citizenship but rather about needing a passport which will facilitate international travel like the Canadian passport will. NOT the same as needing citizenship for the job (contrary to much wishful thinking otherwise common in the forum); indeed, in many if not most such cases, a U.S. passport would, for purposes of the job requirements, suffice just as well, since again "citizenship" as such is not what is important, but a passport with certain traveling privileges.
It is not for-sure this will not qualify for urgent processing, BUT . . . well, most indications are the odds are NOT good.
