On almost all cars spark plugs are easy to replace with some basic tools and a plug socket, and almost anyone can do it. You'll want to make sure the area around the plugs is clean so you aren't dropping grit into the engine. As others say a squirt of penetrating oil a few hours before is a great idea. It is normal that little bit of force is required to get them to free, they aren't finger tight.
I'd be shocked if your 22 year old car was still on its original plugs, depending on mileage and how regularly it's been maintained it may several sets in. Unless you suspect this car has been neglected there's no reason to think that your plugs will be seized. They may not even need replacement at all, but there's no harm in checking as you can just put them straight back in if they are good.
Other things to check while you are looking at the plugs are the spark plug cables and the plug sockets. Any signs of wear, fraying or oil soaked cables mean they need replacement. The sockets that connect to the plugs can get gunk or corrosion on them, if it's there it should be visible and you can clean it off with some electrical contact cleaner and cotton swabs.