Are you talking about a flat or a house?
The ground rent, and how much it can increase, are set out very clearly. Some ground rents are extortionate but you know that upfront - there is no situation where the lease says the ground rent can go up by x and then it goes up by 10x.
The real problem is the managing charge. In most cases, leaseholders have no control whatsoever. The freeholder is the managing agent, cannot be fired if it does a poor job, gets kickbacks from insurers, and if the charge go up by 10% every year there is very little you can do. Eg see this recent article on the Financial Times: www.ft.com/content/b135b814-dc9e-4abc-bb64-f378d11179d8
Many people say: "charges have been reasonable until now, so nothing to worry about". That's the wrong attitude. The real question is not (only) how much have charges been until now, but how much can they increase in the future? Specifically, does the lease give leaseholders any control over the charges? if the managing agent does a poor job yet keeps increasing the cost, do leasehodlers have any recourse or must they suck it up? These are the questions one should ask a solicitor.
Me, I would never ever ever consider living in a newbuild ike those described in the FT article. The risk of being ripped off on charges is too high. I woud consider another kind of leasehold property only if a solicitor can explain to me why a predatory freeholder couldn't profiteer from me. Also bear in mind that freeholds are sold all the time, so a decent freeholder can sell to a non-decent one any time.