I’ve personally never felt much difference with anal-specific lubricants. Normal lubes will work fine, but a conversation about her specific curiosities in that area sounds worthwhile if you haven’t approached it in thag way already, as the first few times can be unbearable if you’re not into it.
Worth her trying herself in an unthreatening space with a toy or several that she’s personally interested in. Let her approach it in her own way first.