You should be able to jump into this hole or 1 block up and a slab above as shown in the image... However this is not the case. You can not jump into it. In Bedrock Edition, you are able to do this. In Java edition you cannot.

I have done a lot of testing and found that the exact jump height is 1.2522033. More accurate found by Jarl-Penguin: 1.252203440253726651

How I figured this out:
I used boats with no gravity to figure this out.
You can use these commands to summon boats to test this.
1.

/execute align xyz run summon minecraft:boat ~ ~-0.8147033 ~ {NoGravity:1b}

2.

/execute align xyz run summon minecraft:boat ~ ~-0.3147033 ~ {NoGravity:1b}