Harold hit it, as usual. ; )
That is the main thing, see this document also, case #1 it explains it.
https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/213935-configuring-non-path-computation-element.html
Elvin
As an additional comment, I posted an external article on CCO related to dynamic BGP SRTE policies, https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/213934-understanding-bgp-dynamic-segment-routin.html.
HTH,
Elvin