In regard to will the planned upgrades fit and will the PSU be OK for the graphic card - the GTX1650 - providing it is the standard 1650 that only draws 75W from the slot and does not require a separate power connection - the answer is YES
In regard to is it worthwhile - the answer is it depends on cost and what you expect to gain
DDR3
out of date chipset
Intel H81
do not expect it to perform like a present day computer
These links will help
Solved: Inspiron 3847, CPU upgrade worth it? - Dell Community
Intel Core i34150 Processor 3M Cache 3.50 GHz Product Specifications
Intel Core i74790 Processor 8M Cache up to 4.00 GHz Product Specifications
same 1150 socket
GeForce GT 1030 | Specifications | GeForce (nvidia.com)
GEFORCE GTX 1650 (nvidia.com)
CAUTION Check measurements of planned card and present card
The present one MAY NOT be a standard 1030 but one with the same chip manufactured for DELL and MAY be smaller
Inspiron 3847 Specifications (dell.com)
Intel H81 Chipset Product Specifications
===============
So the main question is cost to you and what you want to gain from the planned upgrade
Presuming you are on a spinning hard drive you would definitely benefit from a SSD for general performance but not especially for gaming
So - more info from you is needed to give you a more positive answer.
IMHO - unless these parts are going to be available to you - at really low cost, it is not likely to be worthwhile
In regard to is it worthwhile - the answer is it depends on cost and what you expect to gain
DDR3
out of date chipset
Intel H81
do not expect it to perform like a present day computer
These links will help
Solved: Inspiron 3847, CPU upgrade worth it? - Dell Community
Intel Core i34150 Processor 3M Cache 3.50 GHz Product Specifications
Intel Core i74790 Processor 8M Cache up to 4.00 GHz Product Specifications
same 1150 socket
GeForce GT 1030 | Specifications | GeForce (nvidia.com)
GEFORCE GTX 1650 (nvidia.com)
CAUTION Check measurements of planned card and present card
The present one MAY NOT be a standard 1030 but one with the same chip manufactured for DELL and MAY be smaller
Inspiron 3847 Specifications (dell.com)
Intel H81 Chipset Product Specifications
===============
So the main question is cost to you and what you want to gain from the planned upgrade
Presuming you are on a spinning hard drive you would definitely benefit from a SSD for general performance but not especially for gaming
So - more info from you is needed to give you a more positive answer.
IMHO - unless these parts are going to be available to you - at really low cost, it is not likely to be worthwhile