Depends how good a runner you are, Plus how well you run after the bike. It will be hard running after cycling, but don’t panic, it’ll get better after a few minutes. Depending on the length of the bike it may be beter to where running shoes on the bike, with old fashioned toe clips, to save time in transistion.
Elastic shoelaces save a few seconds… all depends on how long the cycle is whether it’s worth changing shoes. On offroad duathlons I tend to just use flats and trainers, on road I’ve always tended to change.
I’ve done a few races and I’m not a great runner so the third leg is always painful. A few brick sessions beforehand help to get your legs used to it. A quick cadence with short strides for the first km of the second run can help..