this formula removes up to one line break when reading the string from cell AC19:
=IFERROR(LEFT(AC19,FIND(CHAR(10),AC19)-1) & " " & RIGHT(AC19,LEN(AC19)-FIND(CHAR(10),AC19)), AC19)
CHAR(10) is the character used for line break within a string.
The IFERROR statement is used to bypass strings without a line break.
If you could have more than one line break per cell in some cases, I suggest to use a three spets approach instead of just one formula because of the large number of cases to be rspected: First, determine the different CHAR(10) positions, then cut the string on all positions and finally combine these parts together again.