In the real F-18, the Target Aspect (TA) pointer shows where YOU are in relation to the target. This means if you are STT mode and you turn, the TA pointer should not follow your turn and also the Gs you are pulling should not show up on the Target.
In DCS F-18, if you are in STT and you turn the TA pointer will follow your turn and the "G" pointer will also follow your turn and will show up if you pull too many Gs.
Although this document is for the T-45, it perfectly explains TA and exactly what it is.
https://www.cnatra.navy.mil/local/docs/pat-pubs/P-825.pdf
This is probably the most relevant part.
Unlike changes in bandit heading, TA will not change immediately with a change in fighter
heading. Rather, with a bandit on a constant heading, the movement of the fighter through space
in relation to BFP is required for the fighter to affect TA