I have setup an RV120 here in my lab and checked to see if it had this setting. On the latest firmware it doesn't, so went back to 1.4.10, and it still does not have the VLAN option for access rules.
If you'll notice on the page you link it talks about version 18.104.22.168, which is not available for the RV120W, the closest one was the 22.214.171.124. I believe the other version number refers to an RV220 firmware version.
Then I noticed that page in the SBKB is for settings on the RV120 and RV220, which while they are similar in most configurations, do not both have inter-VLAN access rules, only the RV220 has those.
I apologize for any mixup here, if you do need this option you can open a case and put in a feature request, although I cannot give you any kind of implementation timeline, or even if it will be added.
Your other option is an RV220W. We do have several other routers that have this feature, but admittedly the datasheets only say access rules, not where they can be applied. I am going to compile a list of our routers that have this feature and will post it here once I complete it.
Sorry for the inconvenience,
Christopher Ebert - Advanced Network Support Engineer
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