How to make (link)button function as hyperlink?

You can use OnClientClick event to call a JavaScript function:

<asp:Button ID="Button1" runat="server" Text="Button" onclientclick='redirect()' />

JavaScript code:

function redirect() {
  location.href = 'page.aspx';
}

But i think the best would be to style a hyperlink with css.

Example :

.button {
  display: block;
  height: 25px;
  background: #f1f1f1;
  padding: 10px;
  text-align: center;
  border-radius: 5px;
  border: 1px solid #e1e1e2;
  color: #000;
  font-weight: bold;
}

There is a middle way. If you want a HTML control but you need to access it server side you can simply add the runat="server" attribute:

<a runat="server" Id="lnkBack">Back</a>

You can then alter the href server side using Attributes

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
       lnkBack.Attributes.Add("href", url);
    }
}

resulting in:

<a id="ctl00_ctl00_mainContentPlaceHolder_contentPlaceHolder_lnkBack" 
      href="url.aspx">Back</a>

The best way to accomplish this is by simply adding "href" to the link button like below.

<asp:LinkButton runat="server" id="SomeLinkButton" href="url" CssClass="btn btn-primary btn-sm">Button Text</asp:LinkButton>

Using javascript, or doing this programmatically in the page_load, will work as well but is not the best way to go about doing this.

You will get this result:

<a id="MainContent_ctl00_SomeLinkButton" class="btn btn-primary btn-sm" href="url" href="javascript:__doPostBack(&#39;ctl00$MainContent$ctl00$lSomeLinkButton&#39;,&#39;&#39;)">Button Text</a>

You can also get the same results by using using a regular <a href="" class=""></a>.