This online application will allow you to generate Stat Blocks ready to print.
As a reference, in the rules Passive Perception ranges from 5 (Gas Spore) to 36 (Tiamat)
You can use some HTML codes in the features description, like "<em>...</em>" to make a text italic.
If you want to start from a rule stat block, you can enter the URL of an existing creature on AideDD, such as "https://www.aidedd.org/dnd/monstres.php?vo=goblin". This will copy all site data into the Stat Block Editor.
See the MONSTERS 5E link in the top menu to access AideDD database.
To save your stat block in PDF format, PRINT from your browser then in 'destination' select SAVE AS PDF instead of your printer.