OP, if you have a computer now that is doing the job, you don't need to replace it now. If fans seem louder now than in the past, consider removing the screws on the bottom (not difficult) and getting the (likely) accumulated dust out of there, particularly the fans. Lots of computer cleaning videos on YouTube will show you how.
Bigger screen could be realized by buying a nice external and attaching your Mac to it. That does not necessarily have to be the relatively pricey ASD though it could be. When you need a bigger screen, use it like a desktop with a relatively gigantic screen. 15"- while bigger- won't really feel that much more spacious then 13". But 27" or bigger will definitely be noticeable. I picked up a
5K2K ultra wide 40" for my desktop screen and could never go back to 27" near "square" like the one in ASD. 16" MBpro screen feels positively tiny when I have to switch to it on the road. You might opt to put the not-needed-right-now Air budget towards a much more expansive screen when needed.
Your needs are NOT CPU/SOC demanding, so that 2019 is plenty for them. Use it until the wheels fall off or perhaps until it no longer gets security updates, which will probably be about 2026 or so. When you are forced to replace- be that planned obsolescence or just an outright conk- buy your replacement then. Be sure you have a backup regularly running (like the easy Time Machine option) so that you can easily recover from a conk scenario.
And while this very Apple-centric crowd is recommending only Apple (surprise, surprise), your demands are such that you could replace with a PC and either spend much less than buying Mac or buy much more power + RAM + storage for the Mac replacement money. PC has much competition for laptops, RAM, SSD, etc so one can get much more for their money by leaping over the wall. Not all PC vendors take nearly half of what we pay as profit. Buy a PC and nearly all of your money is actually buying the PC itself.
Contrary to popular spin, PCs and Windows 11 are just fine, do NOT require a nuclear reactor for power, will not cause 3rd degree burns on the lap and do not sound like a 747 jet engine in use. The one you have now is basically a PC that happens to run macOS. Does it require any of that nonsense people sling around?
That shared, if you are married to Mac or bust, by the time you actually need to replace the one you have, consider hitting the refurb store and buying what will probably be the M4 or M5 MBair at the time. Apple refurb is as good as new and again, your demands don't have anything that requires "latest & greatest" SOC inside. If you've purchased some bigger screen desktop monitor back in 2023 for when you need a bigger screen, it should easily switch to being usable on the new one too when that time comes.
If you must have a new computer now, I suggest hopping into the Refurb store for fairly meaningful discounts. That will let you immediately save 10%-15% vs. Apple new pricing.
