Regex.flags

flags($flags)

Add modifier flags to the regex pattern.

m - Multi-line mode. ^ and $ match the beginning and end of each line within the string. By default ^ and $ match the beginning and end of the entire string.
s - Single-line mode. . matches any character, including newlines. By default, . does not match newlines.
i - Ignore case.
x - Ignore whitespace and comments. Use rx'''...''' for a multi-line regex.

$pattern = rx'Hello World'.flags('is')

'hello'.match($pattern)
//= ['Hello']