Combining Frame rates

I have footage from 2 cameras.
Ones filmed in 4k at 25p
The other is filmed in 4k at 24p
How can I edit this footage in one timeline with maximum quality?
Can I edit them both In a 25p timeline?
Should I convert the 24p to 25p? if so how?

Thanks in advance

Can I edit them both In a 25p timeline?

Yes, you can.
Final Cut Pro is pretty good at handling mixed frame rates without you having to do much.
Assuming your timeline is 25fps, any footage that was filmed at 24fps that you add to that timeline will play at the correct speed (i.e. one second of 24fps footage will last one second).
But in order to achieve this, Final Cut Pro needs to make an extra frame each second by analysing the clip and making 25 frames when there were originally 24 frames (it does this automatically).
This can result in "jumps" or "staggers" in the movement.
Luckily Final Cut Pro gives you some options of how it goes about doing the interpolation and you can pick the best method.
Select the clip in the Timeline (or multiple clips) and go to the Video Inspector. Near the bottom of the panel is a dropdown menu called "Rate Conform - Frame Sampling" which allows you to choose the method for the clip. The best choice for quality is usually "Optical Flow". Note that the clip has to be rendered for you to see the result.
Also note that you can do this the other way around i.e. you can add 25fps footage to a 24fps timeline. It just depends what frame rate you want your final master to be.

Here's the relevant section in the manual:
support.apple.com/guide/final-cut-pro/co...b44e/10.6.6/mac/12.6

Note that you don't actually need to render to see optical flow results, you simply need to park the playhead on the clip and allow FCP to analyze it. Any edits to a particular clip will require this analysis to take place again.

I seem to recall some special handling of 24/25 conform, where the clip is sped up or slowed down that extra frame without telling you, which would affect audio. For b-roll, no biggie. But if you've got dialog there could be drift issues.