'+' is dead, but you can (usually?) fake its role via quote-wrapping individual words - it'll force their presence like a full quoted string, but won't require them in sequence.

'-' is still working. It also works with the 'site:' tag, so you can do things like '-site:w3schools.com'.

It’ll work until they launch a Google- product.

I still use them (replace + with quotes around the word), along with searches for quoted words. Sometimes you have to click the "search for what I typed, not the spell-corrected version" button, though.