Car hasn't been driven in over 5 years

You're right about the battery. It will be sulfated and won't take a charge. Beyond that, just try to start it normally once the new battery is installed. If it's a gas engine you can expect to have to crank the engine a little to get gas up to it. You may need to dribble a little gas from a can into the air intake to get it to fire initially.

Many people will tell you to drain the old stale gas out first but that seems to have a lot to do with the part of the country you live in. I have two cars, one with a carburetor and one fuel injected, that both haven't had gas added in well over five years. Both start and run fine. Once you do get this one started, don't panic if performance is substandard until you use up that old gas and get some new stuff in the tank.

If the car sat outside all these years, inspect the tires for signs of cracking, particularly on the sidewalls and edges of the tread. That's an indication of dry-rot and can lead to a sudden tire failure.