Is it possible to convert a .csv file to a new .ods file using a .ots template to create the new file?
Yes, with a little help from a Base file. Data in csv, Base treats the csv as raw data of a pseudo-database, you can link raw data coming from tables and query of a Base file to Calc’s database ranges.
[Example] Loading CSV into preformatted spreadsheets
Personally, I do not touch any csv with Calc. I handle these database exchange files exclusively in Base.
P.S. Quite often people export csv from their own database in order to import the csv into a spreadsheet. Better connect a Base document to your database and link a spreadsheet’s database range directly to some database query without any csv file, refreshable via menu:Data>Refresh or with a single line of macro code.