for the entire existence of STO, I have not seen a single project that was successfully launched. This is an invented abbreviation that causes interest among stupid investors. Money is not insured here and smart people already realized that this is a simple scam scheme.
There are some projects of STO that has succeeded in the past that probably is not documented due to strict regulations. You definitely not heard some of them because maybe they were not listed on popular sites such as coinmarketcap.
Here are some of them:
Blockchain Capital
Nexo
The Art Token
Lottery.com
Hack fund
Spyce Vc
Mt. Pelerin
Neluns
Aspen Coin
Polymath
Provenance
And many more.
Indeed true,these are some projects that uses an STO way to raised funds and now they're all successfull and soaring. STO is just not a popular like ICO and IEO but it is the most secured way to invest your money.