I have a bunch of bright white cardstock. Is there something I can add to make it glossy like glossy card stock so I ended up with a bunch of bright white card stock I want to print trifolds on. Since I want to use up this paper, is there anything I can get to add onto the paper AFTER the print job that will add gloss to it?

Want to see if I can DIY before I go and buy glossy paper.

Bonus points if there is something that I can add to the paper BEFORE printing (on an inkjet printer)

I tried some basic Mod Podge, but haven't used the clear spray stuff.

I used this for what it is worth: https://www.hobbylobby.com/Scrapbook-Paper-Crafts/Glues-Adhesives/Liquid/Mod-Podge-Gloss/p/80649315?gclid=EAIaIQobChMImsKT5Z_z3wIVlR-tBh0vSwJ7EAQYAiABEgJZDfD_BwE
Have you considered using a high-gloss clear spray paint?

And I would suspect that gloss = plastic to some degree, and an inkjet printer basically sets down ink droplets. If you print on glossy paper that's not specifically designed for inkjet printers, you might end up with a smear of ink. So I'd suggest do printing first, then if you use spray paint you could possibly do several pages at once. 

Bonus perk of post-print gloss: inkjet ink doesn't always stay put (can be smeared by malicious fingers), so glossing the paper afterwards will help seal that ink in.

HTH