Children who struggle with separation at bedtime are usually asking for certainty, not extra entertainment. The more we negotiate, the more bedtime expands into a test of whether the connection will stay available.
Try a ritual you can repeat word for word: one cuddle, one phrase, one promise about what happens next in the morning. Repetition makes the message believable.
It also helps to place the comforting object before the parent leaves, not after the tears begin. Calm tools work best when they are part of the routine, not only the rescue.
If the fear is intense or persistent, talk to a pediatric professional. Bedtime support should feel reassuring, not isolating, for parents too.