Does Libre Office have an invoice template? Windows 10
common. Are you sure you need a template for Impress, Draw or Math?
Please edit your question to tell which component you use for you invoices: Writer, Calc or Base? Mention also your OS and LO version. Simultaneously, retag to replace
common with the component (target application) name.
Don’t use an answer (this is a Question & Answer site, not a forum). Answers are reserved for solutions.
Take a look at Extensions » Extensions
In addition to the question which component (Writer or probably Calc) you want to use to finish and to print the invoice, you need to make clear where the data needed to accomplish the “template” will come from.
Do you want to enter everything manually?
Are there data maintained in a database? Which ones? In what way?
Do you have something like an “amateur database” in spreadsheets?
Invoice templates cannot work “standalone”. They need a data supplier - and they need to be prepared for a specific supplier specifically.
Using the link by @anon73440385 you will get an impression of what I wanted to tell you.
Many years ago there was a template on the OpenOffice.org site called invoice easy. It is still in the authors website but it is in sxc not odt. I last used my copy a couple of years ago and it still worked then.
.sxc is the ODF 1.0 format. Have a try to see if it can still be read by “modern” LO version. Otherwise, download an “old” version (some in the 5.x series should work) to make the conversion to .ods.