Hi Elizabeth,
Unlike the classic experience of SharePoint Online list, in the new experience, the text in a list column will not wrap unless we choose Multiple lines of text when creating the column (and select Enhanced rich text in Additional Column Settings).
In the new experience, the column width will not save based on the last change we made.
To see all the content in a column, we can select the item and click Open the details pane button on the right.
Given this, I would suggest you vote in the uservoice link below or you may post a new idea.
Possibility to choose to wrap text of column text (header but also the text in the datafields)
Regards,
James