try common warm

Lemon, ginger + honey tea (or something with a mixture with like tumeric and stuff), some mint teas, and paracetamol/ibuprofen preferably with some kind of decongestant. Bonus points if you make a honey lemon honey tea with some liquor mixed in.

My partner swears by gargling saltwater for anything upper respiratory-related.

Otherwise, plan on eating a lot of soup for a few days. If you have a really bad cough, mixing booze and honey might work. (My grandpa swore by Portuguese brandy and honey. He kept a bottle hidden away that I am pretty sure would have worked as a Molotov cocktail as-is.) If you can get NyQuil and just sleep it off for 14 hours at a time, that's probably your best bet. It's basically a time travel potion.

To everyone recommending vitamin c: there is no evidence that it does anything but making your pee slightly more expensive unless you have a deficit, which you don't, because you'd notice your teeth falling out.

Liquids, rest, ibuprofen and wasting around for a week is all we got. Pseudoephedrine medication if it's really bad and congested or you need to stand upright for three hours because something can not wait.

Get well soon.

I once mixed an industrial quantity of turmeric with hot milk and honey the same day I got symptoms and the next day I was fine.

You can use a cotton swab to put something like a tiger balm under your nose to relieve a runny nose.

What I'll sometimes also do is take an antihistamine. It'll dry out your nose as well. It supresses the immuno response so it's probably not the best idea. But it can help with your sleep if you take one before bed.

Got recommended the hot toddy by a friend when I had a horrid cold. A fairly classic home remedy similar to what other people have said.

My science brain says no, but got dang if they didn't make me feel better.

Dayquil

Tylenol for headache and fever, pedialyte or it's knockoffs for electrolytes, spicy soups to help drain the runny nose for a while as well any med with Guaifenesin can help thin out heavy mucus. Lemon ginger honey tea always helped and as people have said you can add some whiskey to make it a hot toddy. Antihistamines can also help in some cases with headaches (clariten or generics of the same name, avoid benadryl unless you want to knock yourself out also some decongestants are a combo of gaufensien and antihistamines).

Saline spray or a nedi pot.

Eat a banana (potassium) and drink as much water as you can. Lay on a towel and pile on the blankets. Sweat it out.

No home remedy but lemsip cold and flu tablets generally have worked pretty well for me in the past. For a light cold it largely deletes the symptoms completely. Combine with any variety of tea and honey and you should be able to get some functionality back

Camomile tea! With lemon and brown sugar. It's also really nice just to drink.

Maybe this can help with the runny nose at least https://m.youtube.com/watch?v=gg8TWB7ux4s
Anyway make sure to stay hydrated. Steamy showers are also good at clearing sinuses.

If you can get a proper Lion's Mane extract (that is actual fruiting body and not one of the scammy "100% of the mushroom" ones), I've found it really helps with various kinds of brain fog - a bit like caffeine, but subjectively feeling more like "health" than "energy".

Tullamore Dew, according to my late grandmother

Not much of a home remedy, but if I ever feel even a hint of sore throat/coughing or whatever I immediately start ODing on vitamin C (not literally. Also literally doing so is very hard anyway. Also also not a doctor, etc.), start chugging water, I try to down enough to keep my stomach full and keep over drinking whenever I take a normal drink, if anything hurts I take DayQuil or if unavailable I take acetaminophen or ibuprofen in that order. I also experimented with gobbling zinc (normal consumption amounts in throat lozenges).

When I had a "you can take zero days off!" job I went 4 years and I don't think I ever took a sick day. One time my boss literally forced me to go home. (Taking sick days is good/normal, I was just being a young dipshit, but the vitC, water, pain management combo definitely helped me through 99% of common cold symptoms)

Benadryl at night helps if your allergies are bad enough

Some edutainment-acquired knowledge: Cold lasts about a week on average, if you take vitamin C and zinc that time supposedly is cut short by about half a day.

It's not readily available but a dropper of oil of oregano can wallop (for me) most ailments north of the chest.

Drinking tea til my piss is tea

Paracetamol and Ibuprofen