Multiline regex within a cell in Google Sheets

Cells in Google Sheets can have multiple lines of text, and sometimes you need to match an expression over these lines. REGEXEXTRACT, REGEXMATCH, and REGEXREPLACE don’t match new line characters with .-expressions by default:

You can add the s flag to match multiple lines in the same cell:

So if you want to match regular expressions against multiple lines in Google Sheets, use this formula:

=REGEXEXTRACT(A1, ".(?s)(.*)")

The full regex syntax used by Google Sheets can be found here: https://github.com/google/re2/wiki/Syntax