>>13221584>>13221600>>13221673>>13221702assuming similar density, mass 3x would have volume 3x and therefore radius cbrt(3)x
surface gravity factor would be M/r^2 and thus we can say surface gravity increases by cbrt(x) for x scaling factor of mass/volume assuming constant density. Therefore surface gravity of 3x mass earth-like planet would be ~1.44g or ~14.1m/s^2
Life could be very similar to here on earth. Also, keep in mind that relative densities is all that really matters in terms of buoyancy. A more massive earth-like planet will have a more massive ocean/atmosphere and thus will be just as easy to float/fly through. Buoyant force scales exactly with surface gravity. Land animals like those on earth would be less capable of being large, sure, although it is likely this "new" environmental pressure would just select for what would be to us novel innovations in biology/physiology. It is sufficed to say this is all assuming evolution, a non-flat earth, and gravity to all be true, which of course non of them are.
