Im looking for something like this: https://learn.microsoft.com/en-us/aspnet/core/mvc/views/tag-helpers/built-in/partial-tag-helper?view=aspnetcore-6.0#view-data

but when testing <div epi-property="@Model.CurrentPage.ImageAsContentReference" view-data='@(new ViewDataDictionary(ViewData) { {  "width", 300 },{ "height", 300},{ "format", "webp" } })' />

it is rendering

<div view-data="Microsoft.AspNetCore.Mvc.ViewFeatures.ViewDataDictionary">      ... content comes here ... </div>

We wanted the block to know their context, so we ended up using TempData in the MVC Views...

TempData["whereAmI"] = "left";
Html.PropertyFor(m => m.CurrentContent.LeftContentArea)

and then in the block view:

string whereAmI = TempData["whereAmI"] != null ? TempData["whereAmI"].ToString() : string.Empty;
    

With tag helpers you dont necessarily need to even use additional properties like this. For instance, in your example:

@Html.PropertyFor(m => Model.CurrentPage.ImageAsContentReference, new { width = 300, height = 300, format = "webp"});

At least for the width and height, you can just add them to the tag:

<div epi-property="@Model.CurrentPage.ImageAsContentReference" width="300" height="300" />

Im a little less clear on the format property, so in that case, that might not work. What does that tag do? You could conceivably make a custom taghelper just to handle the 'format' piece. So, your taghelper would target a div and render certain attributes depending on the value. So, two tag helpers on the same tag. Im fairly certain that would work.