Some interest in possession trusts do contain powers to advance capital to the life tenant but this is a special discretionary power exercised by the trustees. After the period set for the life tenant ends, the trust assets will pass to the remaindermen who will take the trust assets outright.
Interest in possession trust
Such a trust allows a beneficiary known as the "life tenant" to enjoy a right to income or to enjoy the occupation of a property which belongs to the trust during their lifetime. It is an absolute right during their lifetime but the life tenant does not own the property outright.