There's nothing feminine about being a bisexual guy. Sounds like you want to be androgynous or something. For clarification: I'm not saying bisexual men can't be feminine. I'm saying the two are unrelated.
If you want to lean andro, take tips from alternative communities.
General high level concepts of how to femme yourself up-
Wear more jewelry (necklaces, rings, bracelets, chains, charms, pins), more of it should be of a feminine style (thinner, more dainty/smaller)
Get more piercings if you're into them, especially kinds of piercings that men rarely get - belly button, nose, cheek, etc.
If you only get your ears pierced wear larger or more prominent ones, not just studs
Wear things that are outwardly cute - flowers, cutesy drawings, etc. and clothing with feminine styles - bows, frills, ruffles, lace
Expose more skin, and wear clothing that's cut for women or exposes skin in ways that feminine clothing typically does
Wear colorful and longer socks, expose them
Scarves and boas when its cold
Shorter shorts, skirts, or unisex clothing
Feminine shoe styles if you can afford them - dainty sandals, heels, etc.
Wear makeup. Eyeliner is perhaps the easiest to get away with as many alt communities like goth wear eyeliner
Paint fingers/toes
Grow longer hair, spend more time styling your hair
Wear scents, especially more feminine ones (mostly stay away from sandalwood), if you're into them... keep them light and airy don't apply them super heavy
That's true and I can kinda see why you'd get that from OP's post but to be fair, OP never actually claimed it did either. They just asked two separate questions.
Turn up the pants and show some ankle. Thats all i got. Its mainly come from memes, but now i love showing off my ankles and notice other people that do 🤷♀️
Wear the colors of the bi flag? Whether in an obvious way, like a shirt, or in a more subtle way with accessories: socks, bracelet, phone wallpaper, keychain..
Necklaces, bracelets, nail polish, finer fabrics... I don't know anything about fashion, just naming stuff that I find pretty. Sorry for being vague, but I'd suggest you start looking for all sorts of different fashions across the board and see if something calls out to you. You're looking to express yourself after all.
Only one way to find out! And i'd say polish is a good way to gauge. Can blame it on someone else (oh my friend wanted to practice or something) and its easily removable if it does end up being a big deal for your parents