TimelineIndicator is the marker. variant="dot" is a small dot, icon is a round badge for an icon, and tile is a rounded square for lists of records, like transactions. tone colours it: primary, success, warning, danger or muted. Use one variant per list so the text lines up.
Each marker draws a line down to the next one, so the line stops at the last item by itself. Turn it off with connector={false} on Timeline. The gap between items is the bottom padding of TimelineContent.
Wrap each run of items in TimelineGroup with a TimelineGroupLabel heading, like one section per day. Without sections, put the TimelineList straight in the Timeline.