Hi @Ckingdom16 as a fellow user I sometimes use this search link (below) to see if a stock is available on a specific account (ISA/Invest/CFD):
https://www.trading212.com/en/Trade-Equities?tab=isa
This should lead you directly to the ISA part.
As a rule of thumb, all stocks available in an Invest account are available in ISA, except the following:
-ADRs/GDRs of non-HMRC compliant exchanges such as most chinese stocks (Nio, Tencent, etc… a notable exception is Alibaba) as well as those from other countries such as Sea Limited.
-OTC stocks