Is he in a Reception class?
Sharing books with him is the most important thing - and non-fiction, not only stories. I think traditional books are preferable to 'apps', but then one can't halt the progress of 'Tech'.
Encourage construction, Duplo, Lego, making jigsaw puzzles, role-play, playing in the park/garden. And don't neglect number work, counting one-to-one correspondence, 'tea party, how many cups, plates are needed? Share biscuits amongst so-many teddies, etc.
This is useful book that will support him through primary school and beyond:
An inexpensive and easy to use book, that can encourage children with reading, spelling and writing, and really help them to understand Phonics, is reviewed in the MN Book Reviews section. Just search ‘Phonics’ and my name.