When you do a final once over of the terms before you sign, double check the numbers. I've heard some stories of finance managers slipping in extra fees or charges, and it may be a headache to get them removed or refunded after the sale has been completed.
It's the finance person's job to sell you extras that profit the dealership. They'll explain extended warranty options, maintenance package options, preventative treatments (rust inhibitor/undercoating, wax/ceramic/sealant options, etc.). Possibly even stuff like paint protection film, tint, or "blackout packages" (dealer subcontracts another company to do custom cosmetic work like painting chrome emblems black or wrapping chrome trim in black vinyl), but these are sometimes unique to the dealer.
As far as cost:
Maintenance packages are usually too expensive to be worth it. If you let someone else do basic maintenance for you, be prepared to check to make sure they actually did the work (check the engine oil dipstick after service, mark your tires before tire rotations, etc.). On top of that, the dealer uses service appointments to upsell you on other service you may not need, like fuel treatments or cabin air filter replacements.
Extended warranties are always negotiable, try to aim for half of the advertised price if you want it. Most people here would suggest skipping the extended warranty, opting instead to put that money aside as an emergency repair fund, because you may never need to use the warranty. It comes down to peace of mind and personal preference.
Preventative treatments, PPF, appearance packages, and even OEM accessories are usually not worth the cost from the dealer, and can be applied or sourced after the fact on your own, for lower prices. But you can always try to work them into your deal. For example, back in 2018 I was able to get PPF, premium floor liners, a cargo mat, and a cargo net all included for free.
If you're interested in any of these things, it would be a good idea to research pricing and service from other companies outside of the dealership so you're more prepared to make a decision when the finance manager pitches these items to you during the sale. Keep in mind that the dealer will often take the lowest bid from a subcontractor to increase their profit.