https://www.instagram.com/reel/DIn-EomoyfO/?igsh=MWJuN3E5bjg4NXIybA== This is worth a try. Like Sera said, try different bottles. MAM worked for us!
At 4mo, you could try introducing a cup rather than a bottle, might work better! X
I had this issue was trying for months to get him to take one. Had to keep persisting trying everyday and eventually he took one. Only one he would take was Lansinoh.
I had this issue with my LO who is also 4 months! It was trial and error with him. I tried different types of bottles and teats at different temperatures. I would give him a small bottle once a day just to get used to him having a bottle. Eventually he finally took to the Fred & Flo baby bottles (I just bought them on a whim)! Now he’s taking a bottle a few times a day! Hopefully you will have some luck with your LO soon