There is an icon on the right side of the Serial Monitor toolbar that controls whether the Serial Monitor output field scrolls down automatically as new content is received:
There is a bug that causes the scroll to not completely go down to the bottom of the output. But that bug was already fixed after the time of the Arduino IDE 2.0.4 release. So if that incomplete scroll is a problem for then you can use the latest nightly build of Arduino IDE, which contains the fix. The nightly build download links are listed here:
I realize that. But this is likely an "XY problem".
The problem (Y) is stated clearly:
The request (X) is likely only a potential solution to Y, rather than being something that is wanted for its own sake.
So instead of just replying "no, Y is not possible", I'm offering a real solution to X.
Do you really think it would be useful? I'm not aware of any application that does bottom to top output printing and can't think of a reason for having such a thing.
I can understand but maybe the answer could be done in other way. For example: This feature is not available but you can enable this option to scroll down automatically.