Only thing I can add to caulking, be careful on the outside of the window frame when you close it (not the window part that opens and closes, the frame itself), there are usually little weep holes that allow water to drain out of the window casing and back outside. If someone installed them wrong and caulked over the holes or they're clogged the water can backup and seep back inside

https://brennancorp.com/blog/are-weep-holes-a-problem-on-replacement-windows/#:~:text=Weep%20holes%20are%20small%20openings,drain%20water%20from%20your%20windows. .