A bit of a hack...
Put your dates in column A. In column B, enter the following formula in the B2: if(weekday(A2,3)=0,A2,"")
Select A2, go to the cell formatting panel, "Conditional Formatting", "Add Rule", "Dates", "The date...", click the cell icon on the right side of the condition box, enter B2, pick a color. Done.
Now, select A2 and do a fill of all the other cells in column A.
With formula above, every cell that is a Monday will have the text in the selected color.
Select the B column and hide it.
ADD: in the formula, the return values are 0=Monday, through 6=Sunday, adjust accordingly for which day to highlight. Can also define custom fill color (bottom of the dropdown list in the rule where says "Bold") vs. text color, to sorta simulate a border.
ADD2: or can switch to LibreOffice. Free, open source, open format, and has the ability to create conditional formatting for a row.