As justme said, those big spikes you are seeing are ringing, not ripple. In fact, what you have there is really ringing imposed on your ripple.
For typical DCDC convertor output, you should expect ripple frequency on the order of your regulator switching frequency (Typically 1-5 MHz) with a peak to peak voltage on the order of 5-20 mV.
I cannot see your full test setup, but typical probing technique is not adequate for this application due to the low voltage and presence of high frequency noise.
You need an extremely short ground conductor connected to ground as close as possible to your test point to avoid coupling high frequency noise through your ground loop, which acts as an antenna. I recommend the paperclip method shown in the link below:
https://training.ti.com/power-tips-measuring-vout-ripple-dcdc-converters
Long probe conductors also increase ringing by adding inductance to the signal path (Together with stray capacitance you get resonance effects and ground lead corruption that cause the ringing to blow up your oscope output).
This will reduce the ringing quite a bit, but to see the ripple only you will want to either bandwidth limit you oscope to (Typically) 20 MHz, or else build an external filter if you don’t have this function.
Finally, using active probes instead of passive will improve things further as you reduce the capacitance effects added by the probe.
For full explanation of all these effects (Ground lead corruption, etc.), see:
https://www.electronicdesign.com/technologies/test-measurement/article/21799660/oscilloscope-probes-influence-measurements
There are some good app notes out there from TI, etc. for further info if you search for “measuring dcdc converter output ripple”
Cheers!
