what size is 20pt

Question: what size is 20 pt?
Answer: This depends on the default size you choose for normalsize and the document class you use.

E.g. article, report, book and letter

\LARGE and normalsize 12pt will be 20 pt

\huge and normalsize 11pt or 10 pt will be 20 pt

If you are are looking for more combinations of classes and commands which will lead to a size of 20 pt just take a look here.