Plus Points work similar to upgrading with points where there’s usually a waitlist (unless PZ or PN class is available in which case it’s possible that saver awards are also available and may be of better value, but not always.) only that there’s no copay like on upgrade with regular points. You book a regular ticket (revenue only) just like anyone else can upgrade you with points, they can also do PP for you. If waitlisted, they’ll clear within 24hrs of the flight usually right before the flight unless the passenger has status.
PP prices do not vary by fare class, but by cabin class and route alone. F,K,G it’s all the same. Upgrades with regular points it does vary, both the points amount and the copay amount. See links below.
Using regular points- basically check here you may be better off with regular points. You can also just check your itinerary in manage my booking once you book to see exact prices and copays.
https://www.united.com/en/us/upgrade-awardsPlus points prices
https://www.united.com/en/us/fly/mileageplus/awards/upgrades-types/pluspoints.htmlIn this you’ll find upgrade priority list
https://www.united.com/en/us/fly/mileageplus/upgrades.html