"Computer years" isn't a really objective thing.
In "computer years," a 5-year-old computer in 2008 would be "very old." There were a lot of substantial improvements between 2008 and 2013. In the 2010s, less so. And now? In the age of Apple Silicon? Not really. You only should upgrade from a 2021 M1 iMac if your current iMac is not working for your business needs or if certain apps are no longer compatible with your computer (which is not the case for any M1 machine right now—those still get all updates). Your Mac MIGHT not support the latest Siri AI features, but unless you're pining for those, you're fine.
I have a 2021 M1 Pro Mac and I will probably keep it for another 5 years at least.
On the printer thing…what brand do you have? the ONLY brand worth getting is a Brother printer (specifically a laser printer). Best printers ever—probably closest thing to an Apple-quality printer in terms of it "just working." I am using a 2011 printer (yes, a printer that is 15 years old) and it works SO well. Zero issues. With my 2021 Mac.
And best part is I got it for probably like $60.