Well the probably obvious thing about “lo-fi” productions, is the lack of highs and lows. This means not worrying about the “sub” frequencies, you can probably use any eq to roll it ,off around 40-60Hz. Roll off the highs to taste.
Alternatively, you could go with a vinyl vibe, even tape. So you could try out the J37, Kramer Tape & AR Vinyl. I’d be selective of where you put them though, because you can have too much of a good thing and it will totally kill your production.
Drums and possible bass, in particular benefit from that vinyl vibe as it’s a throw back to when people were sampling their beats to produce these type of productions. Often they’d layer it with an electronic drum too. Other instruments will benefit too, if you want that classic “sampled loop” sound.
To save yourself from having CPU expensive plugins all over your mix, you could always group them on instruments logically and use them that way. You could even over do the effect, run it in parallel, and bring it up to taste. You will probably still need to manage the highs and lows of the original tracks, so they aren’t too “high fidelity”
I’d also consider mixing with a lot of classic eqs and compressors, like the V Series, or SSL E, which would include the MixHub. Consider also using 80s-90s style effects. Forget about your lush reverbs and delays, go for something a bit more grainy and low-fi. You can bit crush a modern reverb, or perhaps find Its or emulations of the classics. I think H-Reverb has some good presets, and has a “lo-fi” bit crushing effect too. IR1 might have some decent IRs of classic gear too. H-Delay also does lo-fi.
But you can use anything you can get your hands on really.