Auto remove an html attribute from a site I don't own

I am using a site that hosts it's videos via iframe on vimeo. For some reason they disabled Picture in picture mode which I really need. I can reenable this feature by removing an html attribute via devtools locally. Is there a good way to automate this process.

Note: The "dev" of the site is not capable of making any changes on their end. I only need to remove this attribute once it hits my browser

Edit: The tag I need to edit an attribute of is a video tag. I use chrome but any browser will do. OS is Windows 10

Without more information about the HTML in question, the specific tag that needs to be removed, your browser and operating system, here is a general answer.

You may use the browser add-on Greasemonkey to modify the HTML code before it executes. For Chrome the extension is called Tampermonkey.

This is basically JavaScript code, called userscript, that's injected into the HTML and can modify almost all aspects of the document.

For a more specific answer, please give more information.