Enable dropdown option based on meeting a condition of another column value

[karthik thenparai]

In the list, I’ve a column “Review Status” as drop down option having below options.

To be reviewed, WIP, Benefit validation, Finance sign off. 

I’ve another column in the list “Annualized benefit”.

My requirement is: When Annualized benefit field value is >=$50k, then only i want the Finance sign off > $50K drop down option should be enabled for the user to select it.

Is it possible with designer or with validation formula? I dont have infopath.

[#2]

Since you are talking about SPO, you can only do this in two possible ways:
(1) By customizing your form with programming (sorry, but avoid the use of Designer for this)
(2) By customizing your form with PowerApps

[#3]

1. Is the feature not available in designer and hence you recommend other programming? If yes, what program do you refer here?
2. Power apps - is it a licensed one? Can you also tell What steps to be performed once installed it?

[#4]

Ey Karthik, glad to help:
(1) SharePoint Framework (SPFx) is what you have to look at and SPFx extensions
(2) PowerApps are available by default in Office 365. An example of what I mean: http://www.itidea.nl/index.php/how-to-create-cascading-drop-downs-using-powerapps/

[#5]

My requirement is slightly different from dependent data validation. The field [annual benefit] is a user entry field and if the value entered is = or > 50000, then only I want the drop down option "finance signoff" in [review status] to be enabled or available for the user to select.
Looked at the power apps example, I haven't seen it in my windows 10 system!!! Where should I spot?