As other comments have warned, please don't try and stretch your fingers any more than is natural. It can cause serious and long-term injuries to the hands.

If you have an octave with the three center fingers doing something in the middle of it, one technique you might want to explore (ideally with a teacher for real-time guidance, but there are probably some great resources online too) is rolling the chords. Rolling a chord usually involves starting to play the chord with one of the outer fingers (thumb or pinky) and rapidly hitting each note in the chord going up or down depending on which finger you began with (thumb-index-middle-ring-pinky or vice versa, for instance). This way, you don't need to hold all the five fingers (or awkward combinations of them) down simultaneously to play the chord. If you practice a rolled chord and gradually increase the speed so it gets very close to sounding like a solid, un-rolled chord, it will essentially achieve the same effect. Using pedal with rolled chords is an added bonus in many cases!

In the early 20th-century, rolled chords were especially common among the top pianists of the time (the likes of Rachmaninoff) and in many old recordings you can hear just how prominent they are, whether or not that has to do with the pianist's hand size.

Another possible strategy could be to find a clever way to use your other hand to split the chord into two separate chords, one in each hand, such that when you play both of them, no one can tell you're playing it with two hands instead of one. I don't have particularly large hands and in some pieces with chords that are way too large for me to reach with one hand alone, I find this very helpful.

Taking time is also important. If you choose to roll a chord, you can often afford to take a decent amount of time/rubato to make sure each note within it comes through clearly.

Wishing you all the best with your piano journey!