is it true that spanning tree loop never occur if all links are using port channel?

[martlee2]

is it true that spanning tree loop never occur if all links are using port channel?

if it is true, does it mean that no need to apply loop guard and root guard for all port channels?

[Joseph W. Doherty]

If port-channel is working as it's supposed to, the physical links in the port-channel will operate as a single link.  So, whether a port-channel creates a L2 loop depends on your overall topology, and again, that everything is working correctly.

Even if a specific port-channel is working correctly, something like Loop Guard can protect your from other link issues, i.e. including non-port-channel links.  Ditto for Root Guard.  I.e. both Loop Guard and Root Guard are intended to preclude issues beyond those of a problematic port-channel.