How to do a boolean search in LinkedIn fits on one line: quote each title, join its spellings with OR in capitals, wrap them in parentheses and put NOT after the group. The hard part is the spellings. A quoted "VP Sales" matches that phrase exactly, so someone whose profile says Vice President of Sales never shows up, and nothing tells you they are missing.
The builder above lists the spellings a title is written in and writes the finished string. It runs in your browser, and nothing you type leaves the page.
How to read the spellings
Read them before you copy the string. An abbreviation can stand for more than one job: CSO is strategy, security or sales, and the builder adds every meaning it knows, so remove the ones you do not mean. VP Sales and VP of Sales are different phrases to a quoted search, so keep both forms when a title can take "of".
A finished string looks like this:
("VP Sales" OR "VP of Sales" OR "Vice President Sales" OR "Vice President of Sales") NOT (assistant OR intern)
Every spelling sits inside one group, so the NOT applies to all of them.
When the string does not work
These rules come from LinkedIn's help article on boolean search:
Lower-case operators are read as plain words. Type AND, OR and NOT in capitals.
NOT is read before AND and OR, so a NOT outside the parentheses applies only to the term just before it.
Only parentheses group terms. Square brackets and braces are read as plain characters.
The failure that looks like success is a string with one spelling per title. It runs cleanly, and everyone who wrote the title another way is simply absent.
What to do next
Paste the string into LinkedIn and read the first page of results. Too many people you did not want? Add a word to leave out. Too few? Put back a spelling you removed.
If you want a list of people with work emails rather than a page of results, Oneprofile's Find people takes the titles themselves and finds their common spellings for you, and counting the matches costs nothing. Before you invite anyone, read the LinkedIn weekly connection limit, with its sources.