Welcome @khushbu, to the community!
In some older NUCLEO boards, it was possible to use the included ST-LINK/V2-1 as an independent ST-LINK. With the NUCLEO-G491RE (MB1367) this was no longer provided.
Theoretically, after a cursory glance at the schematics, one could come to the conclusion that by removing SB40, SB41 and possibly other jumper/solder bridges, one could lead out the port of the ST-LINK/V3E. However, it is already difficult with the T_NRST signal, as it is permanently connected to the target STM32 and JP3 separates T_NRST from the ST-LINK. All in all, the effort involved is too great for a conversion of the NUCLEO-G491RE to be worthwhile.
Does it answer your question?
Regards
/Peter