Open the ODT file, you can then go to File > Save As (or 'Save as copy'), you can save to those formats and others:
You can also use 'Export to' and 'Export to PDF' to export to PDF and other formats.
For more information, you can use Help > 'libreoffice help' (or just press F1) - or use the online help (e.g. Save As, Export, Export PDF)
You can also use a command in terminal or a script to convert documents with libreoffice:
libreoffice --headless --convert-to <FORMAT> /<path>/<to>/<file>
libreoffice is the command for libreoffice (or probably libreoffice writer in this case) - this probably could be
soffice depending on how libreoffice was installed
--headless means it won't launch the libreoffice GUI.
--convert-to <FORMAT> - where
<FORMAT> is the format you want to convert to, like
/<path>/<to>/<file> - file to convert - e.g.
~/Desktop/Untitled\ 1.odt or
For more info on this run
libreoffice --help or