aestheticsymbols
Use in a combo

Heavy Greek cross copy & paste

✚ is heavy greek cross, a plain-text Unicode symbol from the Dingbats block. On Aesthetic Symbols it lives in the charms & marks collection, tagged cross. As plain text it takes on the font and colour of wherever you paste it — a bio, a username, a caption or a stream title.

Unicode
U+271A
HTML entity
✚
CSS content
\271A
JavaScript
\u{271A}
UTF-8 bytes
E2 9C 9A
Made of

U+271A ✚ · Dingbats

Will it show up? · Long-established text symbols

Plain-text characters from blocks that mainstream desktop and mobile fonts have covered for years. These are the safe ones.

Worked out from how each character is encoded, not from a test on a real device.