Apple Watches vary in price depending on what you want from them. There is a lot of similarity between the Series 8 and the Series 7 from last year. Do not worry if you own a Series 7 or even a Series 6 from two years ago.
Watch OS 9 also supports Apple Watches dating back to Series 4, so you'll be able to take advantage of several great features like workouts and sleep cycles.
For your first smartwatch, I recommend the Apple Watch SE. I own a first-generation SE and it gives you 80% of what the latest Apple Watch has, but without the sensors for blood oxygen and temperature monitoring and an always-on display. In addition, it's cheaper at $249.