How do I fix these??

So no one is coming out cause of COVID and I need to do this. I already have the paint for the areas (3 windows like this).



My plan is to clean the surface after scraping with a putty knife to remove chipping/old paint...I'll be cleaning with water + soap.....each window (theres 3). Then I need to "fill in" the missing wood...this is where I hit a stump. The thing that worries me is the wood at the bottom pulling away...I bought a wood filler tub thats paintable..but the crack seems rather narrow...I don't think Zip Loc will work to get wood filler in the gap. What to do what to do? I do have to paint the whole square area around the window....I was thinking of exterior caulk...or even normal caulk...but then again ....is it paintable? What if it shrinks??? etc.

https://imgur.com/a/C0oHsej