It will vote for Trump for sure, but the margin will be telling. My precinct was 61-32 Trump (slightly less Republican than Williamson County as a whole) and 74-25 Romney. Bill Lee and Mark Green also both got 61% of the vote here (Blackburn did worse, but still won it by 12 points), so 61% seems like a good baseline. It was a little bit more Republican again for this year's Congressional primary ballot preference, but I'll say Trump matches his 61% from 2016, with most of the undecideds going to Biden.
61-37 Trump, the same as Lee vs. Dean, seems fair. I anticipate that Williamson County will look a lot like the Lee vs. Dean race too (65-33 Lee). But, if Trump drops into the 50s in my precinct, it's probably indicative of a significant Democratic suburban swing (even outside of the rapidly trending Texas suburbs).
EDIT: I do think Hagerty will overperform Trump pretty significantly here (even though it was a very strong Sethi precinct in the primary). Including downballot races, I'll say something like this:
PRES: Trump 61, Biden 37
SEN: Hagerty 66, Bradshaw 28
HOUSE: Green 64, Sreepada 34
ST HOUSE: Casada 57, Madeira 30, Fiscus 13 (not really sure how strong the Fiscus candidacy will be, but he seems more serious than most Independents)
I was a little optimistic on all but three House race, which I got exactly right.
President: Trump 58, Biden 40
Senate: Hagerty 63, Bradshaw 34
House: Green 64, Sreepada 34 (exactly correct)
State House: Casada 52, Madeira 32, Fiscus 15