No, you cannot convert a UK Visit Visa to a UK work Visa while in the UK. The UK does not allow any conversion of a UK Visit Visa into a Work Visa while a person stays in the country. The Standard Visitor Visa serves only for tourists and business visitors and family guests thus people cannot work in the UK while holding this visa. In order to obtain work permission in the UK you must first go to your home country and get a work visa such as the Skilled Worker Visa before you can work and live in the country.
The application process requires three primary elements which include a job offer from a UK-based sponsor together with salary requirements and eligibility standards and submission through UKVI from any country except UK.