PS4 upgrade games on PS5 Question

I bought Insurgency Sandstorm on PS4 to play on my PS5, & I noticed it doesn't look as nice as I think it should so maybe running at PS4 settings.

I have an external 4tb hdd hooked up for all my PS4 games to load onto to leave room for PS5 on it's p!ssy small insufficient ssd...My question is, do the PS4 games that have PS5 upgrades run with said upgrades off the external standard hdd, or do they need to be running of the PS5's internal ssd to get said benefits?

I played my PS4 copy of GOT the other day & I couldn't notice any difference from when it was running off my PS5 directly.

what is actually problem I an not understand please elaborate