Howdy
gajugrah and welcome to BYC
If I may, I would also be a little concerned about the coop size for 3 x LF’s and also the security of the run you currently have but, having said that, some concerns may be allayed by your location.
For example, here, due to our climate, the coop is only ever used for laying of eggs and sleeping, the rest of the time is spent in the run or out on supervised free range. So, while they obviously still need room in the coop to sleep, lay eggs and move around etc, as they do not spend much time in there, it does not need to be huge.
If you live in a climate that requires them to spend time in the coop for warmth, shelter etc, if they do not have enough room, they may squabble and start feather picking and worse out of boredom.
With the security of the run .. again, here, that would be minimally OK as I work from home and live in an area that has next to no predators; my biggest risk would be an overfed neighbour cat or stray dog BUT there is always the risk of aerial predators, Hawks for example. So, while it would be OK here, I prefer to be safe not sorry and have a secure, covered run. Also, the extra security in the run including a cover, helps to keep out unwanted, freeloading feed and egg stealers like Crows.
Depending on your circumstances you may wish to secure the run a bit more.
Lastly, I started with only 2 pullets and sadly, one passed away leaving one on her own. She was very sad and I had to dash out and find her a companion quickly; lucky I was able to do that. So yep, I think getting the extra one is probably a good idea in that you will have that ‘buffer’ should you need it.
Good luck with whatever decision you make and enjoy your girls .. be warned, they are addictive