Custom Snippets

would have the possibility to have custom snippets in heid?

There is a snippets functionality in HeidiSQL. See it when right-clicking the query editor, then click "Save as snippet". So what do you mean by "custom" snippets?

thank you so much! would you be able to call these snippets in the editor with the autocomplete "ctrl + space"?

No, Ctrl + space is for making suggestions on the code under the cursor.