For context: I am not a web developer or programmer of any sort and I use a screen-reader.
I am using an accessibility evaluation tool across some sites I'd like to visit, which, however, have some accessibility issues.
From some googling, I see that it is fairly easy to specify a single webpages language by using <HTML lang='en'></html>
for example for English.
How easy would it be to implement this across an entire site with hundreds of separate pages? This is a very vague question without linking to the specific website. For example, a car website with a separate page for individual cars with each page missing a specified language. Would it be fairly simple to specify the language across all automatically or would one have to manually copy/paste <HTML lang='en'></html>
for each page? Or does it heavily depend on how the website was structured HTML-wise? etc.
Thank you