How to increase font size for autocomplete data for TextBox?

Question

How to increase the font size of a custom startup in a text box?

I am extracting some autocomplete data from a database, but using a font from a text box. In this case, this font gujarati, and the font makes the autocomplete text invisible. My code is below:

private void txt()
{
    AutoCompleteStringCollection ff = new AutoCompleteStringCollection();
    DataSet ds = new DataSet();
    ff = new AutoCompleteStringCollection();
    string sql = "select distinct p_name from product_master";
    OleDbCommand cmd = new OleDbCommand(sql, con);
    OleDbDataAdapter da = new OleDbDataAdapter(cmd);
    da.Fill(ds);

    for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
    {
        ff.Add(ds.Tables[0].Rows[i]["p_name"].ToString());
    }
    txtRxName.AutoCompleteCustomSource = ff;
    txtRxName.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
    txtRxName.AutoCompleteSource = AutoCompleteSource.CustomSource;
}

In the above example, I want the text in my car computer to be larger.