I'm in roughly the same boat, new to .223 as a hunting round. In addition to the wisdom above, there's some great info here:
https://www.nzhuntingandshooting.co....23-deer-64884/ and also found some great info here:
https://www.ballisticstudies.com/Kno...Remington.html
From what I've read so far:
1. shot placement is critical (i.e. knowing where to hit and ability to hit it);
2. know the limitations of calibre/projectile (range and lethality), and;
3. be willing to let something walk on if it's not within (ethical) range, or doesn't present a clean shot.
My very non-scientific analysis has noticed that people on this forum who successfully use .223 on deer, all appear to have high levels of knowledge and experience... which sort of says it all.
Looking forward to hearing how you get on!