She has done the whole 5k in the past. Generally in fits and starts with stops to inspect interesting rocks etc. We usually did around 45-50 minutes and she got offered to stop at any lap point. She refused of course, but would always want to stop at the furthest point on the course from the car, so was expected to keep going back to the car. I need a decent reserve of pace if she decides she wants to go because she's quick if she wants to be.
Her longest walks (in hills) have been 10 miles and walked up Ben Lomond last summer, far less tired than either adult (we shared the big rucksack with 2 year old). So covering 5k at whatever pace she fancies isn't "tough" for her. I preferred quieter parkruns where there were laps (drop out options) but where the numbers were low or paths wide (or laps worked out right) - didn't want to be overtaken by the busy 25-28 minute pace bunch as she's not always good at running in a straight line...
I expect her to be capable of a "steady" 30 minute 5k in a couple of years because she's leggy and likes exercise - and if under exercised is rather "entertaining" to be around - lots of leaping off all the sofas. She does tennis and will do more non-running stuff once it all opens, but at the moment running (generally off road) is the way I can keep her interested.
DH takes the kids to run in the local skate park first thing while I do a steady run, so she does not do "distance" training with me.
Thanks to chasing her, 2 yo is getting quick too - he's already faster than my walking pace if he wants to go (ie not where or when I want him to!!!).