How can i exchange my iMac(M1 basic model) to another model?

If you bought it directly from Apple (retail store or online) in the US, you have a 14-day "no questions asked" refund period to return the computer for a refund. The you can buy the one you want. See:

Returns & Refunds - Shopping Help - Apple

If you bought from an Authorized Reseller, the reseller's return policy applies.

If you are outside the 14-day grace period or the reseller does not allow returns, all you can do is sell the computer privately.

If you're beyond the 14 day no questions asked return date you have another option. You can go to this Apple page, Apple Trade In, to see how much you'd get on a trade in. You would probably lose more than the dock that Keith linked to would cost but I don't know what you concern is with your current M1.

If you are past the 14 days, a thunderbolt dock like this:

https://www.owcdigital.com/products/thunderbolt-3-dock-14-port

might solve your problems. It has ethernet and an USB3 USB-C port.

Trade-ins aren’t allowed on the latest models.

I always order my Macs from Apple's online store so I can customize it exactly how I want it with the options Apple has available. While this may take a bit longer due to Apple having to custom configure my Mac it is always well worth the wait.

About the only time I visit an Apple store is if I have a hardware problem such as the other day one of my AirPods Pro decided to die, as it was under AppleCare I took it in and after a brief test I walked out with a fresh pair. The only thing that was not exchanged was the case itself. Oh, and in my haste to get out I left my car keyes there and then left the store. My wife wanted to visit a few other stores in the vicinity and I forgot about the keyes until it was time to leave. Fortunately I had put a AirTag on the key ring and it was instantly tracked to the Apple Store. Good thing too, my wife would have killed me if I'd lost my car keyes as we were going out for our wedding anniversary dinner and had a reservation to meet.

What kind of trade in can you get on it? Any where close to the cost difference of the dock with Ethernet and other ports, USB C and Thunderbolt?