No. In general, you cannot switch to another visa from inside the UK after entering with a UK ETA.
A UK ETA is an electronic travel authorisation for short visits to the United Kingdom.
It is used for limited visit purposes such as tourism, visiting family, short business trips, or transit.
If your purpose changes to work, long-term study, or long-term stay, you usually need to leave the UK and apply for the correct UK visa separately.
If your purpose is not a short visit, you should check whether you need a proper UK visa before traveling instead of relying on a UK ETA.