I could modify her, but sexual predatory behaviour is key to describing Succubus.
Since you have said that you're a new DM, you may not have thought about this, but you can always reskin a monster to be something else. You keep the stats but change the descriptors on them.
For example - if you like the idea of using rakshasa, the creature could be a "minor rakshasha" - a very weak version of the type, or perhaps a regular rakshasa that has for some reason been cursed and is at substantially lower power, forcing it to remain hidden from it's enemies. So going that route, I would modify the succubus as:
Shapechanger - no need to change this, rakshasa are classic shapeshifters
Claw attack - no need to change this either - rakshasa also have a claw attack in their demon forms
The remaining attacks are not part of the typical "rakshasa" toolkit, but rakshasa's typically have spellcasting ability and succubi don't. So you can think of them as the only "spells" it can use in its weakened state, or you can just think of them as psychic powers that are unique to this particular rakshasa (and possibly why it's been cursed in the first place):
Charm - mechanically you don't need to change this. Descriptively, this might be a bit more "look into my eyes, you are in my power" Bela Lugosi Dracula than how I'd run it with a succubus for adult players, but the mechanics are sound.
Draining Kiss - here's the one that you need to change - but again only descriptively. Instead of a kiss, the rakshasa just needs to touch a creature that it has charmed and pummels them with a psychic attack. The mechanical effects are the same since there's nothing about them that screams "succubus".
Etherealness - Rakshasas can plane shift, but in its weakened state it can only reach the Ethereal and back - no real need to change this one beyond that.
Telepathy/Telepathic Bond - Not really a rakshasa thing, but I'd personally keep it. It fits with the Bela Lugosi version of Charm and I'd handwave a justification for it - maybe that this particular rakshasa is unique (though to be honest, I make each of my rakshasa unique anyway when I use them, so it wouldn't be an issue for me). You could drop it entirely if there isn't a plot reason that the creature requires it.
And with that you've got a monster that mechanically is still the same creature in the adventure but fits the story you want to tell better. If you don't like rakshasa, it could easily be a special kind of shapeshifting vampire, an alien cthuloid monster in disguise, a powerful "master doppelganger", or something else entirely.
Reskinning creatures is a really powerful tool in the DM's toolkit.