Thank you very much for your examples with RegEx and efforts to bring the topic closer to me.
Unfortunately, I’m afraid I’m more confused now than before.

Ctrl+Enter (in Multi-line mode) = \n (in Single-line mode).

If I do CTRL + ENTER as in the picture above, I won’t get any results with the following options:
☑ Multiline
◉ (None)
◉ Regular Expressions
◉ Escape Sequence

Is this a bug of EmEditor or an application error of mine?
Are multi-line queries only allowed with the option ◉ Regular Expressions?

If you want to search for a multi-line string, usually you have to match the exact number of the lines:

Does this mean that I have to go to the end of each text document before searching to determine the exact number of lines?

And note that EmEditor cannot highlight multi-line matches with colors.

Mmmh, with
☑ Multiline
◉ Regular Expressions
in a .txt file the numbers 2 and 4 are marked in green.

In the example in the picture I wanted to find exactly the numbers 2 and 4 in a range from 1 to 5, with or without RegEx.
To complicate matters, I would also like to add the number 24 to the list and this number should not be marked.
Unfortunately, I do not know how it would be possible to make an exact definition, so that only numbers 2 and 4 would be marked.

Perhaps it would be possible if you or someone else could answer these questions for me.