I think Samsung Goodlock and one of it's plug ins allows the space bar to be made bigger @robo650
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.
@robo650: You may also wish to check out your options via Settings > General Management > Language and Input > On Screen Keyboard > Samsung Keyboard > Style and Layout > Size and Transparency & Keyboard Font Size, to see if this helps. For Size and Transparency, turn the phone to Landscape view and you will be able to adjust the keyboard size and, in turn, increase the size of the space bar.