I am looking for a cheap phone which doesn't lag! (previous mi phone freezes a lot so not interested in mi phones) and will be mainly used for social media.
Dunno if this helps but I am a big fan of the Motorola series. Love the no frills near stock android flavour. Not the greatest of cameras, features and specs but it works for me. Its cheap, I can change it every 2 years and I don't have to bother with bloatware and the nagware that I hear a lot of the low and mid rangers suffer from.
+1 for Motorola. I would say, increase your budget and get a Moto G40 fusion. Given its near stock android, experience should be smooth for social sites.
Another option is Samsung F12, but I would keep it as a last option since it's 4gb ram and you will experience lag after some period.
I got a couple of Nokia 3.2 phones for my mom and aunt for around 8k over a year ago. Works well for their basic usage which includes YouTube, Facebook, WhatsApp etc with no lag yet.
It recently even got android 11 update which surprised me.
Main thing to note is this model only has 2.4ghz wifi and not 5ghz but they don't even know or care about it.
Don't know what the latest models are for under 10k though.