OEM products (dell, hp, etc), are usually limited on what upgrades are possible, best to contact them.
Generally, retail purchase of some OEM component products is not widely available.
My PC- Ryzen 5 5600x, B550 aorus pro ac, Hyper 212 black, 2 x 16gb F4-3600c16dgtzn kit, NM790 2TB, Nitro+RX6900XT, RM850, Win.10 Pro., LC27G55T.