Are you meaning about auto-investment of the dividend? If so, there is a topic here where you can add your vote.
Strictly speaking, dividends are paid based however the company pays decides to pay them. Most pay in cash, occasionally some in shares. In some instances companies do pay scrip dividends - where you have the option to receive the dividend in the form of additional shares instead of cash (scrip dividends aren’t yet supported by Freetrade though).