What were the reforms made by William Taft during his administration?

William Taft, following on the heels of the progressive reform president Theodore Roosevelt, continued into the Taft administration many of the reforms proposed by Roosevelt. It is fair to say Roosevelt paved the way for progressive change, and Taft was quick to seize momentum in the Congress for reform. Differing from Roosevelt and probably why Taft does not earn the same acclaim as Roosevelt for reform, Taft's focus was directed at administrative aspects, as opposed to Roosevelt's broad political reform agenda. Reform movements often start with visionary leadership and then give way to the pragmatic implementation of the desired reform outcome. This in no way disparages the administrator from the visionary. Without both reform remains an elusive ideal. While Roosevelt earned his reputation for his attacks on monopolies through anti-trust regulations and was nicknamed the Great Trust-Buster, the Taft administration prosecuted 99 cases of trust violations—many more than that under Roosevelt.
Taft's main thrust was in domestic affairs to shore up the economy. Taft was an executive at heart and attacked with gusto technical issues like tariffs. A special Congress convened during the early part of the Taft administration to address issues related to tariffs and to reduce the impact of tariffs through lower fees. He made changes reorganizing the government that added civil service protection to postal workers. Taft's single most heralded legislation accomplishment was when he signed the Mann-Elkins Act of 1910, which had two main effects. The first was authorized the Interstate Commerce Commission (ICC) to establish and set rail rates. The second was the ICC's role expanded to cover telecommunications. Some historians credit passage of the act to fostering expansion of telecommunications across the country, as for the first time there was a clear set of rules and authority for settling disputes in the industry.
There are many other technical reforms Taft made through the continuing expansion of the administrative rule and authority. Taft found the execution of the law through the regulatory agencies much less of an impediment to reform than going through the political machinations of Congress.
https://millercenter.org/president/taft/domestic-affairs

https://www.ushistory.org/us/43e.asp

https://www.whitehouse.gov/about-the-white-house/presidents/william-howard-taft/