Filtered colimits commute with finite limits in any Grothendieck topos. A Grothendieck topos does not need to be locally finitely presentable; the presentability rank of a topos is tightly related to the structure of its site presentation, as shown in Prop. 5.5 of the preprint
Gabriel-Ulmer duality for topoi and its relation with site presentations, Ivan Di Liberti and Julia Ramos González, arXiv:1902.09391.
Indeed I must confess a conflict of interests, as I am one of the authors of that preprint.
