Do I need to bring photocopies and a photo when getting my tourist visa extension stamp in Thailand?

there is no final stamp on a tourist visa extension. A tourist visa extension is a 30 day extension issued on the spot.

What it sounds like you applied for was a 60 day covid extension (you can tell by READING your current stamp and seeing if it says "application for extension under consideration until xxx")

IF you have an under consideration stamp you just go back to the immigration office where you applied for that extension on the date the stamp tells you to with your passport and the blue/green receipt showing you paid the 1900baht. They'll stamp in the extension stamp for free

Are you referring to a Tourist visa extension - which generally is a one step process adding 30 days to your existing stamp or a “Covid extension” which is often a 2 step process where you get an under consideration stamp for 7-14 days and then have to return for the remainder of the 60 days stamp?

No. Just your passport