col_names = 'Name', 'Surname', 'Telephone'
table = document.add_table(rows=1, cols=len(col_names))
hdr_cells = table.rows[0].cells
for idx, name in enumerate(col_names):
    paragraph = hdr_cells[idx].paragraphs[0]
run = paragraph.add_run(name)
run.bold = True
Bold a table cells