Reported speech - statements whose meaning still stands
The default is that, in the words of the ‘Longman Student Grammar of Spoken and Written English’ (LSGSWE), ‘the tense of the verb in the indirect quote agrees with the past tense of the reporting verb’. That is the case in ‘He said he liked pizza.’
However, the LSGSWE goes on to say ‘although this use of past tense in reported speech is common, reported speech also occurs with other tenses’, and gives examples in which ‘the reporting verb is in the past tense, but the verb in the indirect quote remains in the present tense, emphasizing that the circumstances expressed . . . are still continuing.’ That seems to be the case with ‘He said he likes pizza.’