So I have modded Bethesda games (easy with the kits) but I want to get into modding the Sims 4.

Specifically I am wondering (unless somebody already knows of this) a mod where when you offer your wrist to a Vampire, you don't get the Recently Bitten moodlet.

Is that something a beginner could do?

Thanks in advance for any suggestions.

Sims 4 is luckily very beginner friendly to mod The vast majority of things are controlled in XML tuning, which is a readable format that you can learn intuitively rather than needing previous coding knowledge.

Removing an effect from an interaction would be straightforward. All you need is a tool like Sims4Studio to modify the 'loot' data for that interaction, which is basically the list of things that are distributed by an interaction.
There is an online tuning file browser as well, for quickly combing through files with the input of EA's TDESC (developer notes on what each function does): https://tdesc.lot51.cc/builder
From File > Import EA Tuning, you can use keywords to find the tuning file(s) you need. I was able to find this interaction from typing in 'permission' to find loot_VampireDrink_WithPermission, which is where that buff is defined.

In Sims4Studio, all you have to do is go to Tools > Create Empty Package, name and save it, then Tools > Extract Tuning... and search for that same resource and add it to the package. The XML data will show in the right-hand pane and can be freely edited. Remove the unwanted buff, making sure not to break any unrelated brackets- you can use the plus and minus button on the first part of a code snippet to get an idea where it ends and another part begins.
Alternatively, you can make edits directly in the TDESC Builder and click Download Tuning, then import that into the package.

Then you just save and drop the package you made in the Mods folder

Thank you so much!