The method used on my Samsung s20fe is either to hold down two buttons at the same time, or to slide the edge of your hand across the screen. The first method is impossible to do unless you are a contortionist, and the second only works now and again.
What made samsung select these I don't know.
On my 2 motorola phones, I just press a button on the edge of my phone and up comes a small menu. Select screenshot and its done. How simple is that?
You can search the play store for 3rd party apps to make screenshot easier, but I understand why you have created the post. I'd you go down the play store route it be a case of trying out the best ones from the highest reviews.
You can use your edge panel, task has a screen shot button you can use. Or the drop down menu you can now add screen shot button there. Press the 3 dots and go on add buttons see if you can add the screen shot button to your drop down menu.
My hands are quite big. About the length of my phone. Yet to discover what an edge panel is and never found a drop down menu. Must investigate. Why this phone cannot use standard Android controls I don't know.