I saw a very interesting blog post this week from Brent Ozar that asked if SQL Server 2019 More CPU-Intensive Than SQL Server 2016? You can read the post, but a client was having CPU issues and thought everything between their SQL Server 2016 and 2019 environments was the same.
Brent decided to test this and found that on identical systems, he has queries taking more CPU on SQL 2019 than 2016. A few commenters tested as well, with similar results. Not everyone had similar results, but most did. You can get the scripts from the post and try it yourself if you have SQL 2016 and 2019 instances.
One would expect that more recent versions would run faster, or use fewer resources, for equivalent data sets and hardware. I know that's not always the case, but it ought to be the case for lots of workloads. If not, then arguably the newer version isn't better. It likely isn't worth more money, and definitely needs more development work. This is my view of Windows 11, which seems to have returned to the habit of earlier Windows version of requiring and consuming more resources than its predecessor.
I don't often benchmark or evaluate SQL Server version. I don't have to make those decisions, but I have seen SQL Server continue to improve on the TPC-E benchmark. However, this isn't necessarily the same hardware. In fact, across versions, it likely isn't. There could be more CPU consumed by the same queries, masked by hardware advances (and falling hardware prices).
Is SQL Server using more CPU in newer versions? I'll let you see if that's the case on your systems. Even if it isn't, you might document some queries (in addition to Brent's) and record the results. That might help you decide when you upgrade.