Roblox offers a feature called a "star code" that allows players to donate to content producers by entering their specific star code during in-game purchases.

Roblox is Ending the Star Codes Program Similarly to Fortnite's Creator Codes system, Roblox's Star Codes enable players to support their favorite creators whenever they purchase Robux or Premium.

Use a Roblox Star code just before purchasing Robux (Image via Roblox) Just before you purchase Robux from Roblox, the option to use a Roblox Star code is available, though it quickly goes unnoticed.