Nope, at least not without either root or a replacement recovery neither of which you likely have or want. It should be possible to image a device then restore to the (exact) same model but I only know of LG having provided for it – perhaps many others did as well and I just never heard of it. Alas such an image might not be useful as sometimes the fix a device receives is a replacement that isn’t the exact same model, usually a newer one but now the image can’t be decrypted or can’t operate the device. If you have repair/maintenance mode that will provide the shop with a basic interface that can’t access your data (and hopefully they would not accidentally completely reset the device anyway), but again if they replace it with a refurbished/new device all your data will be lost so you need to find a way to make a backup.

Stores can have crap in them, don’t go thinking that they are 100% safe. Also anti-virus/malware false positives exist.