Copa America ill include Argentina, Brazil and Uruguay whilst European Championships with 24 teams will mean there are few countries not involved which would include Sweden and uncertainties over whether Wales and Republic of Ireland will qualify.
So the main players likely to be involved on Spurs tours might include :
Goalkeepers - Forster, Austin, Whiteman or Keeley
Defenders - Phillips, Davies (possibly) Porro (last Spanish call up in 2021), Dorrington
Midfield, - Sarr, Bissouma, Skipp, Devine, Bergval
Forwards - Son, Kulusevski, Johnson (possibly), Gil, Parrott, Scarlett,
There might be involvement for a couple of loanees such as Tanganga, Reguilon and Spence whilst a few other u21's might well join the squad including Santiago (several appearances on bench) and a number of others - its not unusual for maybe 6 u21's to be included on a pre-season tour.
So a touring squad of 20 - 25 players is certainly possible even whilst international competitions are going on.