Adding IKEv2 to the list of tunneling protocols wouldn't have an impact on the other connection profile settings that also reference the default policy you are just allowing another tunneling protocol along with the ones you already have enabled.
Although personally I would create a new group policy for the site to site connections just to keep things more organized but if you want to use the default policy that is ok too.
The goal of this guide is to illustrate the main concepts of TrustSec which are:
Classification: Classifying endpoints and servers with a Scalable Group Tag (SGT)
Propagation: Communicating SGT information through the network
Securing the network by ensuring the right users, the right access, to the right set of resources is the core function of Cisco’s Identity Services Engine (ISE). ISE builds context about users (Who), device type (What), access time (When), ...
Segmentation Strategy - An ISE Prescriptive Guide
IntroductionBaseline ISE Configuration for TrustSecActive Directory Integration (optional)Defining the Security Groups (SG) and...