Cannondale optimo 3 (used) vs New Trek Domane

Hi everyone, I am looking for help with choosing a first road bike.

A friend has offered to give me their cannondale optimo 3 size 51cm in good usable condition. The problem is I am not confident the fit is great, I’m 5’6.5 and the reach feels a little aggressive for me and I felt pretty fatigued riding it but I am also not used to road biking. In theory I could invest some money in trying to improve the fit (eg a shorter stem) but would prefer to just get my own bike if it’s just a less comfortable ride (my understanding is this is more of a race bike than endurance but please let me know if I’m mistake?) Photo attached.

Alternatively I am considering just going ahead and buying myself a new trek Domane (just the lowest price base model) which felt a little more comfortable in store but I didn’t get a chance to ride it a distance to really test that out. I also like the idea of getting a new bike with a warranty etc. Open to other ideas for good entry level bikes this is just what I’ve tried so far.

Thanks!